Harnessing Available Evidence in Single-Case Experimental Studies: The Use of Multilevel Meta-Analysis

The use of multilevel models to combine and compare the results of multiple single-case experimental design (SCED) studies has been proposed about two decades ago. Since then, the number of multilevel meta-analyses of SCED studies steadily increased, together with the complexity of multilevel models used. At the same time, many studies were done to empirically evaluate the approach in a variety of situations, and to study how the flexibility of multilevel models can be employed to account for many complexities that often are encountered in SCED research, such as autocorrelation, linear and nonlinear time trends, specific designs, external event effects, multiple outcomes, and heterogeneity. In this paper, we give a state-of-the-art of the multilevel approach, by making an overview of basic and more extended models, summarizing simulation results, and discussing some remaining issues.

A Visual Aid and Objective Rule Encompassing the Data Features of Visual Analysis

Visual analysis of single-case research is commonly described as a gold standard, but it is often unreliable. Thus, an objective tool for applying visual analysis is necessary, as an alternative to the Conservative Dual Criterion, which presents some drawbacks. The proposed free web-based tool enables assessing change in trend and level between two adjacent phases, while taking data variability into account. The application of the tool results in (a) a dichotomous decision regarding the presence or absence of an immediate effect, a progressive or delayed effect, or an overall effect and (b) a quantification of overlap. The proposal is evaluated by applying it to both real and simulated data, obtaining favorable results. The visual aid and the objective rules are expected to make visual analysis more consistent, but they are not intended as a substitute for the analysts' judgment, as a formal test of statistical significance, or as a tool for assessing social validity.

An Examination of Measurement Procedures and Characteristics of Baseline Outcome Data in Single-Case Research

There has been growing interest in using statistical methods to analyze data and estimate effect size indices from studies that use single-case designs (SCDs), as a complement to traditional visual inspection methods. The validity of a statistical method rests on whether its assumptions are plausible representations of the process by which the data were collected, yet there is evidence that some assumptions-particularly regarding normality of error distributions-may be inappropriate for single-case data. To develop more appropriate modeling assumptions and statistical methods, researchers must attend to the features of real SCD data. In this study, we examine several features of SCDs with behavioral outcome measures in order to inform development of statistical methods. Drawing on a corpus of over 300 studies, including approximately 1,800 cases, from seven systematic reviews that cover a range of interventions and outcome constructs, we report the distribution of study designs, distribution of outcome measurement procedures, and features of baseline outcome data distributions for the most common types of measurements used in single-case research. We discuss implications for the development of more realistic assumptions regarding outcome distributions in SCD studies, as well as the design of Monte Carlo simulation studies evaluating the performance of statistical analysis techniques for SCD data.

The cognitive remediation of attention in HIV-associated neurocognitive disorders (HAND): A meta-analysis and systematic review

Background: Despite medical advances in Highly Active Antiretroviral Therapy (HAART), patients living with HIV continue to be at risk for developing HIV-associated neurocognitive disorders (HAND). The optimization of non-HAART interventions, including cognitive rehabilitation therapy (CRT), shows promise in reversing the impact of HAND. No data exist indicating the efficacy of CRT in remediating attention skills following neuroHIV. This paper presents a meta-analysis of randomised and non-randomised controlled trials (RCTs) to remediate attention skills following HIV CRT. Methods: The database search included literature from Google Scholar, ERIC, Cochrane Library, ISI Web of Knowledge, PubMed, PsycINFO, and grey literature published between 2013 and 2022. Inclusion criteria included studies with participants living with HIV who had undergone CRT intervention to remediate attention skills following neuroHIV. Exclusion criteria included case studies, non-human studies, and literature reviews. To assess study quality, including, randomisation, allocation concealment, participant and personnel blinding, the Cochrane Collaboration ratings system was applied. Results: A total of 14 studies met the inclusion criteria (n = 532). There were significant pre- to post-intervention between-group benefits due to CRT in the experimental group relative to control conditions for the remediation of attention skills following HIV acquisition (Hedges g = 0.251, 95% CI = 0.005 to 0.497; p < 0.05). No significant effects (p > 0.05) were demonstrated for subgroup analysis. Conclusions: To the author's knowledge, this is the first meta-analysis that exclusively analyses the remediation of attention skills in the era of HAART and neuroHIV, where all studies included participants diagnosed with HIV. The overall meta-analysis effect indicates the efficacy of CRT in remediating attention skills in HIV and HAND. It is recommended that future cognitive rehabilitation protocols to remediate attention skills should be context and population-specific and that they be supplemented by objective biomarkers indicating the efficacy of the CRT. Registration: Protocols.io (01/03/2023).

A robot intervention for adults with ADHD and insomnia-A mixed-method proof-of-concept study

OBJECTIVE

To investigate individual effects of a three-week sleep robot intervention in adults with ADHD and insomnia, and to explore participants' experiences with the intervention.

METHODS

A proof-of-concept study with a mixed-methods design (n = 6, female = 4) where a repeated ABA single-case study was combined with interviews. Data were collected with the Consensus Sleep Diary, wrist actigraphy, questionnaires on symptoms of insomnia, arousal, emotional distress, and ADHD, and through individual interviews.

RESULTS

Visual analysis of the sleep diary and actigraphy variables did not support any effects from the robot intervention. Half of participants reported clinically relevant reductions on the Insomnia Severity Index from pre- to post-intervention. No changes regarding ADHD or arousal. Thematic analysis of the interviews resulted in three themes: (1) A pleasant companion, (2) Too much/not enough, and (3) A new routine.

CONCLUSION

Adjustments of the intervention ought to be made to match the needs of patients with both ADHD and insomnia before the next trial is conducted.

Effectiveness of training in expressing positive emotions, reacting to change and greeting peers after childhood traumatic brain injury: a single-case experimental study

Background

Social cognitive deficits are common after traumatic brain injury (TBI). The participant in this single-case experimental design (SCED) was 7 years old when he sustained a severe TBI. After 2 years in rehabilitation, he continues to show deficits in social cognition.

Objective

To determine the effectiveness of three interventions, each aimed at improving a behavior altered by social cognition deficits. These behaviors were: (1) expression of positive emotions, (2) reacting to changes in plans, and (3) greeting classmates.

Method

An A-B-A' design was used for each behavior. In addition, each behavior was targeted with a rehabilitation program applied over 10 sessions.

Results

For the first behavior, changes between phases B-A' (NAP = 0.712) and A-A' (NAP = 0.864) indicated improvements in the child's ability to express positive emotions. In the second behavior, changes in the intensity of reactions between phases B and A' (NAP = 0.815) and A vs. A' (NAP = 0.834) indicated that the child adapted to changes in a plan and to unexpected situations in a more adaptive way. For the third behavior, changes in the number of greetings between phases A and B (NAP = 0.883) and A vs. A' (NAP = 0.844) suggested that during the third phase of the study, the participant fully acquired the habit of greeting peers and increased his interactions with others.

Conclusion

While the participant showed improvements in all three targeted behaviors, due to the complexity of the third behavior, it is recommended that in future research, the intervention targeting social interactions should be applied over a longer timeframe to ensure that improvements are more stable in the long term.

Single-case intervention research design standards: Additional proposed upgrades and future directions

Single-case intervention research design standards have evolved considerably over the past decade. These standards serve the dual role of assisting in single-case design (SCD) intervention research methodology and as guidelines for literature syntheses within a particular research domain. In a recent article (Kratochwill et al., 2021), we argued for a need to clarify key features of these standards. In this article we offer additional recommendations for SCD research and synthesis standards that have been either underdeveloped or missing in the conduct of research and in literature syntheses. Our recommendations are organized into three categories: expanding design standards, expanding evidence standards, and expanding the applications and consistency of SCDs. The recommendations we advance are for consideration for future standards, research design training, and they are especially important to guide the reporting of SCD intervention investigations as they enter the literature-synthesis phase of evidence-based practice initiatives.

Implementation of a brief online skills group of dialectical behaviour therapy for emotional dysregulation in Latinx: a withdrawal experimental single-case design

Background:

Dialectical behaviour therapy (DBT) skills groups have shown promise as an effective treatment for clients with emotional dysregulation, especially when combined with individual DBT. However, their efficacy is not well established as an online therapy, or in the Latinx population.

Aims:

This study aimed to explore satisfaction, retention and effects of an internet-based DBT group added to individual online sessions.

Method:

An ABAB withdrawal experimental single-case design was conducted to evaluate the effect of a brief online DBT skills group on emotional dysregulation, anxiety and depression for five Latinx participants. DBT skills group (phase B) were compared with placebo group sessions (phase A) and fortnightly individual DBT sessions were offered throughout to manage risk.

Results:

Visual inspection showed a decrease in level of emotional dysregulation and a large effect size according to the Nonoverlap of All Pairs when comparing group DBT and placebo phases. Although depression symptoms decreased after introducing group DBT, anxiety indicators decreased most during the second round of group placebo sessions.

Discussion:

Whilst only a pilot, this study suggests that online group DBT in Latinx populations is feasible and effective for changing emotional regulation processes but may not effectively target anxiety. Future research might increase the number of DBT sessions in order to enhance learning opportunities and generalization. Replication with larger sample sizes and diverse modalities is needed.

Single-case experimental designs for child neurological rehabilitation and developmental disability research

Single-case experimental designs (SCEDs) are a group of methodologies of growing interest, aiming to test the effectiveness of an intervention at the single-participant level, using a rigorous and prospective methodology. SCEDs may promote flexibility on how we design research protocols and inform clinical decision-making, especially for personalized outcome measures, inclusion of families with challenging needs, measurement of children's progress in relation to parental implementation of interventions, and focus on personal goals. Design options for SCEDs are discussed in relation to an expected on/off effect of the intervention (e.g. school/environmental adaptation, assistive technology devices) or, alternatively, on an expected carry-on/maintenance of effects (interventions aiming to develop or restore a function). Randomization in multiple-baseline designs and 'power' calculations are explained. The most frequent reasons for not detecting an intervention effect in SCEDs are also presented, especially in relation to baseline length, trend, and instability. The use of SCEDs on the front and back ends of randomized controlled trials is discussed.

Integrative couple treatment for pathological gamblers with an emphasis on forgiveness processes: A case study with three couples

Gambling's impact on a couple's relationship is an essential element in the gambling disorder (GD). Gamblers tend to lie to their partner to conceal the extent of their gambling problems and debts, which can lead to a serious relational transgression for the couple. One promising avenue is a couple treatment focusing on forgiveness processes. The objective of this study was to determine whether the Integrative Couple Treatment for Pathological Gamblers (ICT-PG) with an emphasis on forgiveness processes helped couples to enhance these processes. A Single-Case Research Design (SCRD) was used with three couples in which one of the members had a GD. The results highlight the importance of jointly analyzing the forgiveness processes between the gamblers and their partner, which constantly influenced each other. These promising results illustrate the relevance of integrating forgiveness processes in treatment for couples where one of the members has a GD.

Examining and Enhancing the Methodological Quality of Nonconcurrent Multiple-Baseline Designs

In this article we respond to the recent recommendation of Slocum et al. (2022), who provided conceptual and methodological recommendations for reconsidering the credibility and validity of the nonconcurrent multiple-baseline design. We build on these recommendations and offer replication and randomization upgrades that should further improve the status of the nonconcurrent version of the design in standards and single-case design research. Although we suggest that the nonconcurrent version should be an acceptable methodological option for single-case design researchers, the traditional concurrent multiple-baseline design should generally be the design of choice.

A temporal-based therapy for children with inconsistent phonological disorder: A case-series

Deficits in temporal auditory processing, and in particular higher gap detection thresholds have been reported in children with inconsistent phonological disorder (IPD). Here we hypothesized that providing these children with extra time for phoneme identification may in turn enhance their phonological planning abilities for production, and accordingly improve not only consistency but also accuracy of their speech. We designed and tested a new temporal-based therapy, inspired by Core Vocabulary Therapy and called it T-CVT, where we digitally lengthened formant transitions between phonemes of words used for therapy. This allowed to target both temporal auditory processing and word phonological planning. Four preschool Persian native children with IPD received T-CVT for eight weeks. We measured changes in speech consistency (% inconsistency) and accuracy (percentage of consonants correct PCC) to assess the effects of the intervention. Therapy significantly improved both consistency and accuracy of word production in the four children: % inconsistency decreased from 59% on average before therapy to 2% post-T-CVT, and PCC increased from 61% to 92% on average. Consistency and accuracy were furthermore maintained or even still improved at three-month follow-up (2% inconsistency and 99% PCC). Results in a nonword repetition task showed the generalization of these effects to non-treated material: % inconsistency for nonwords decreased from 67% to 10% post-therapy, and PCC increased from 63% to 90%. These preliminary findings support the efficacy of the T-CVT intervention for children with IPD who show temporal auditory processing deficits as reflected by higher gap detection thresholds.

What is the effect of personalized cognitive strategy instruction on facilitating return-to-learn for individuals experiencing prolonged concussion symptoms?

The purpose of this study was to evaluate the degree to which personalized cognitive strategy instruction (PCSI) assisted students with prolonged concussion symptoms (PCS) to achieve functional and academic-related goals. It was hypothesized that goal attainment on collaboratively developed functional goals and selected scores on the pre/post outcome measurements would improve following the delivery of PCSI. A non-concurrent multiple baseline design was utilized across three female participants ages 13-16. The weekly status tracking measurement of participant performance served as the primary measurement analysed to determine the existence of a functional relation between the addition of PCSI to psychoeducation and the achievement of participant outcome. Although visual analysis of the plotted status tracking data did not support the existence of a functional relation, all three participants met or exceeded functional goals on their goal attainment scales. A Tau-U analysis supported a small treatment effect. The positive response to the intervention from two of the three participants in addition to goal attainment for all three participants suggests PCSI has potential to mitigate cognitive challenges in adolescents with PCS. Implications for future research and methods to promote ecological measurement of intervention effects are discussed.

Applied hybrid single-case experiments published between 2016 and 2020: A systematic review

Single-case experimental designs (SCEDs) are frequently used research designs in psychology, (special) education, and related fields. Hybrid designs are formed by combining two or more of the basic SCED forms (i.e. phase designs, alternation designs, multiple baseline designs, and changing criterion designs). Hybrid designs have the potential to tackle complex research questions and increase internal validity, but relatively little is known about their use in actual research practice. Therefore, we systematically reviewed SCED hybrid designs published between 2016 and 2020. The systematic review of 67 studies indicates that a hybrid of phase designs and multiple baseline designs is most popular. Hybrid designs are most frequently analyzed by means of visual analysis paired with descriptive statistics. Randomization in the study design is common only for one particular kind of hybrid design. Examples of hybrid studies reveal that these designs are particularly popular in educational research. We compare some of the results of the systematic review to those obtained by Hammond and Gast, Shadish and Sullivan, and Tanious and Onghena. Finally, we discuss the results of the present systematic review in light of the need for specific guidelines for hybrid designs, including analytical methods, design specific randomization and reporting, and the need for terminological clarification.

Dealing With Autocorrelation in the Single Case AB-Design: A Study Assessing the Mediating Effect of Infant Crying on the Relation Between Responsive Soothing and Infant Sleep

Mediation analysis is widely adopted by researchers to disentangle the causal pathways by which an intervention affects an outcome. This paper describes a model to estimate the direct and indirect effect from a single subject AB-design with repeated assessments of both the mediator and the outcome. We discuss the plausibility of the modeling assumptions and contrast different approaches to deal with the autocorrelation in the time series data. While there are only small differences between those approaches when the number of timepoints is small (T = 15), the Generalized Least Squares approach performs best in medium (T = 30) to large (T = 90) time series. We apply the proposed methodology to data from a single case AB-design that was conducted with a mother of an excessively crying baby. Daily crying and baby sleep during the night were assessed with online diaries during a baseline phase and intervention phase. Between both phases, the pediatrician instructed the mother how to apply a responsive soothing intervention, the happiest baby (THB) method. We find that the direct effect of THB on sleeping is positive. THB also reduces crying but decreased crying during the day is associated with decreased sleeping during the night and hence a negative indirect effect of THB on sleeping via crying is found.

Introduction to the Special Section: Translating Advanced Quantitative Techniques for Single-Case Experimental Design Data

The articles in this special section offer strategies to single-case experimental design (SCED) researchers to interpret their outcomes, communicate their results, and compare the results using common, quantitative results. Advancing quantitative methods applied to SCED data will facilitate communication with scientists and other professionals that do not typically interpret graphed data of the dependent variable. Horner and Ferron aptly note that innovative statistical procedures are improving the precision and credibility of SCED research as disseminate our findings to an increasingly diverse audience. This special section promotes the translation of these quantitative methods to encourage their adoption in research using single case experimental designs.

Assessing Momentary Well-Being in People Living With Dementia: A Systematic Review of Observational Instruments

Optimizing the possibility to lead good lives is at the core of treatment and care for people with dementia. This may be monitored by assessing well-being and quality of life. However, cognitive impairment following dementia may complicate recall-based assessment with questionnaires, and proxy-ratings from family-caregivers do not correspond well to self-reports. Thus, using observational measures represents a potentially advanced option. Systematic reviews evaluating measurement properties, interpretability and feasibility of observational instruments assessing well-being in people living with dementia are lacking. Thus, this review performed systematic searches to find peer reviewed validated instruments of relevance in the databases MEDLINE, EMBASE, PsycINFO, Web of Science, CINAHL and ProQuest. Twenty-two instruments assessing well-being were included for evaluation of measurement properties based on the systematic approach of the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN). The evaluation included risk of bias on study level, and assessment of measurement properties on instrument level including content validity, construct validity, structural validity, internal consistency, measurement invariance, cross-cultural validity, measurement error and inter-rater/intra-rater/test-retest reliability and responsiveness. Additionally, the feasibility and interpretability of the measures were evaluated. No single instrument could be recommended based on existing publications. Thus, we provide general recommendations about further assessment and development of these instruments. Finally, we describe the most promising instruments and offer guidance with respect to their implementation and use in clinical and research contexts.

Investigation of Regression-Based Effect Size Methods Developed in Single-Subject Studies

The purpose of this study is to provide a brief introduction to effect size calculation in single-subject design studies, including a description of nonparametric and regression-based effect sizes. We then focus the rest of the tutorial on common regression-based methods used to calculate effect size in single-subject experimental studies. We start by first describing the difference between five regression-based methods (Gorsuch, White et al., Center et al., Allison and Gorman, Huitema and McKean). This is followed by an example using the five regression-based effect size methods and a demonstration how these methods can be applied using a sample data set. In this way, the question of how the values obtained from different effect size methods differ was answered. The specific regression models used in these five regression-based methods and how these models can be obtained from the SPSS program were shown. R² values obtained from these five methods were converted to Cohen's d value and compared in this study. The d values obtained from the same data set were estimated as 0.003, 0.357, 2.180, 3.470, and 2.108 for the Allison and Gorman, Gorsuch, White et al., Center et al., as well as for Huitema and McKean methods, respectively. A brief description of selected statistical programs available to conduct regression-based methods was given.

Establishment of an International Collaborative Network for N-of-1 Trials and Single-Case Designs

In this article we briefly examine the unique features of Single-Case Designs (SCDs) (studies in a single participant), their history and current trends, and real-world clinical applications. The International Collaborative Network for N-of-1 Trials and Single-Case Designs (ICN) is a formal collaborative network for individuals with an interest in SCDs. The ICN was established in 2017 to support the SCD scientific community and provide opportunities for collaboration, a global communication channel, resource sharing and knowledge exchange. In May 2021, there were more than 420 members in 31 countries. A member survey was undertaken in 2019 to identify priorities for the ICN for the following few years. This article outlines the key priorities identified and the ICN's progress to date in these key areas including network activities (developing a communications strategy to increase awareness, collecting/sharing a comprehensive set of resources, guidelines and tips, and incorporating the consumer perspective) and scientific activities (writing position papers and guest editing special journal issues, exploring key stakeholder perspectives about SCDs, and working to streamline ethical approval processes for SCDs). The ICN provides a practical means to engage with this methodology through membership. We encourage clinicians, researchers, industry, and healthcare consumers to learn more about and conduct SCDs, and to join us in our mission of using SCDs to improve health outcomes for individuals and populations.

Mirror therapy for phantom limb pain in moderate intellectual disability. A case report

BACKGROUND

Phantom limb pain (PLP) is a common problem after limb amputation. There is mounting evidence supporting the use of mirror therapy (MT) in the treatment of individuals with PLP. However, there is no research studying the effects of MT on PLP in individuals with intellectual developmental disorders (IDD). The aim of this study was to increase our understanding of MT when used with adults with IDD and PLP through a case study approach.

METHODS

Here, we describe the use of MT with a 53-year-old female with moderate IDD and PLP, related to her left leg being amputated after ulcer complications. The study followed an A-B-A-B design (baseline-treatment-withdrawal of treatment-re-introduction of treatment), lasting 2 years, which included a long-term follow-up.

RESULTS

The data showed that the PLP sensation decreased after the MT treatment, with a raw change of 3.92 points and a 48% decrease in mean pain intensity ratings from pre- to post-treatment.

CONCLUSIONS

This is a unique case-report on the use of MT with an individual with IDD suffering from PLP. The findings show that MT helped to significantly reduce the intensity of the PLP in this patient.

SIGNIFICANCE

This is a case-report that illustrates how mirror therapy can be applied to people with intellectual developmental disorders and phantom limb pain. The results showed that phantom limb pain decreased after the mirror therapy, with a raw change of 3,92 points and a percent change of 48%.

Comparing Biofeedback Types for Children With Residual /ɹ/ Errors in American English: A Single-Case Randomization Design

Purpose Research comparing different biofeedback types could lead to individualized treatments for those with residual speech errors. This study examines within-treatment response to ultrasound and visual-acoustic biofeedback, as well as generalization to untrained words, for errors affecting the American English rhotic /ɹ/. We investigated whether some children demonstrated greater improvement in /ɹ/ during ultrasound or visual-acoustic biofeedback. Each participant received both biofeedback types. Individual predictors of treatment response (i.e., age, auditory-perceptual skill, oral somatosensory skill, and growth mindset) were also explored. Method Seven children ages 9-16 years with residual rhotic errors participated in 10 treatment visits. Each visit consisted of two conditions: 45 min of ultrasound biofeedback and 45 min of visual-acoustic biofeedback. The order of biofeedback conditions was randomized within a single-case experimental design. Acquisition of /ɹ/ was evaluated through acoustic measurements (normalized F3-F2 difference) of selected nonbiofeedback productions during practice. Generalization of /ɹ/ was evaluated through acoustic measurements and perceptual ratings of pretreatment/posttreatment probes. Results Five participants demonstrated acquisition of practiced words during the combined treatment package. Three participants demonstrated a clinically significant degree of generalization to untreated words on posttreatment probes. Randomization tests indicated one participant demonstrated a significant advantage for visual-acoustic over ultrasound biofeedback. Participants' auditory-perceptual acuity on an /ɹ/-/w/ identification task was identified as a possible correlate of generalization following treatment. Conclusions Most participants did not demonstrate a statistically significant difference in acoustic productions between the ultrasound and visual-acoustic conditions, but one participant showed greater improvement in /ɹ/ during visual-acoustic biofeedback. Supplemental Material https://doi.org/10.23641/asha.14881101.

A Randomized Case Series Approach to Testing Efficacy of Interventions for Minimally Verbal Autistic Children

BACKGROUND

Randomized Controlled Trials (RCTs) are the gold standard for assessing whether an intervention is effective; however, they require large sample sizes in order to detect small effects. For rare or complex populations, we advocate a case series approach as a more realistic and useful first step for intervention evaluation. We consider the importance of randomization to such designs, and advocate for the use of Randomization Tests and Between Case Effect Sizes to provide a robust and statistically powerful evaluation of outcomes. In this tutorial, we describe the method, procedures, and analysis code necessary to conduct robust single case series, using an empirical example with minimally verbal autistic children.

METHOD

We applied a pre-registered (https://osf.io/9gvbs) randomized baseline design with between-case effect size to a case series (n = 19), to test the efficacy of a novel, parent-mediated, app-based speech production intervention (BabbleBooster) for minimally verbal autistic children. Parent-rated probe scores were used to densely sample performance accuracy over time.

RESULTS

Parents were able to reliably code their children's speech productions using BabbleBooster. A non-significant Randomization Test and small Between-Case Effect Size (d = 0.267), suggested there was no evidence that BabbleBooster improved speech production in minimally verbal autistic children, relative to baseline scores, during this brief period of intervention.

CONCLUSION

The current analyses exemplify a more robust approach to examining treatment effects in rare or complex populations, where RCT may be difficult or premature to implement. To facilitate adoption of this method by researchers and practitioners, we provide analysis code that can be adapted using open source R packages. Future studies could use this case series design to evaluate interventions aiming to improve speech and language outcomes for minimally verbal autistic children, and other heterogeneous and hard to reach populations.

A Tribute to the Mind, Methodology and Mentoring of Wayne Velicer

Wayne Velicer is remembered for a mind where mathematical concepts and calculations intrigued him, behavioral science beckoned him, and people fascinated him. Born in Green Bay, Wisconsin on March 4, 1944, he was raised on a farm, although early influences extended far beyond that beginning. His Mathematics BS and Psychology minor at Wisconsin State University in Oshkosh, and his PhD in Quantitative Psychology from Purdue led him to a fruitful and far-reaching career. He was honored several times as a high-impact author, was a renowned scholar in quantitative and health psychology, and had more than 300 scholarly publications and 54,000+ citations of his work, advancing the arenas of quantitative methodology and behavioral health. In his methodological work, Velicer sought out ways to measure, synthesize, categorize, and assess people and constructs across behaviors and time, largely through principal components analysis, time series, and cluster analysis. Further, he and several colleagues developed a method called Testing Theory-based Quantitative Predictions, successfully applied to predicting outcomes and effect sizes in smoking cessation, diet behavior, and sun protection, with the potential for wider applications. With $60,000,000 in external funding, Velicer also helped engage a large cadre of students and other colleagues to study methodological models for a myriad of health behaviors in a widely applied Transtheoretical Model of Change. Unwittingly, he has engendered indelible memories and gratitude to all who crossed his path. Although Wayne Velicer left this world on October 15, 2017 after battling an aggressive cancer, he is still very present among us.

Avoid or engage? Outcomes of graded exposure in youth with chronic pain using a sequential replicated single-case randomized design

Pain-related fear is typically associated with avoidance behavior and pain-related disability in youth with chronic pain. Youth with elevated pain-related fear have attenuated treatment responses; thus, targeted treatment is highly warranted. Evidence supporting graded in vivo exposure treatment (GET) for adults with chronic pain is considerable, but just emerging for youth. The current investigation represents the first sequential replicated and randomized single-case experimental phase design with multiple measures evaluating GET for youth with chronic pain, entitled GET Living. A cohort of 27 youth (81% female) with mixed chronic pain completed GET Living. For each participant, a no-treatment randomized baseline period was compared with GET Living and 3- and 6-month follow-ups. Daily changes in primary outcomes fear and avoidance and secondary outcomes pain catastrophizing, pain intensity, and pain acceptance were assessed using electronic diaries and subjected to descriptive and model-based inference analyses. Based on individual effect size calculations, a third of participants significantly improved by the end of treatment on fear, avoidance, and pain acceptance. By follow-up, over 80% of participants had improved across all primary and secondary outcomes. Model-based inference analysis results to examine the series of replicated cases were generally consistent. Improvements during GET Living was superior to the no-treatment randomized baseline period for avoidance, pain acceptance, and pain intensity, whereas fear and pain catastrophizing did not improve. All 5 outcomes emerged as significantly improved at 3- and 6-month follow-ups. The results of this replicated single-case experimental phase design support the effectiveness of graded exposure for youth with chronic pain and elevated pain-related fear avoidance.

Assessing Consistency in Single-Case Data Features Using Modified Brinley Plots

The current text deals with the assessment of consistency of data features from experimentally similar phases and consistency of effects in single-case experimental designs. Although consistency is frequently mentioned as a critical feature, few quantifications have been proposed so far: namely, under the acronyms CONDAP (consistency of data patterns in similar phases) and CONEFF (consistency of effects). Whereas CONDAP allows assessing the consistency of data patterns, the proposals made here focus on the consistency of data features such as level, trend, and variability, as represented by summary measures (mean, ordinary least squares slope, and standard deviation, respectively). The assessment of consistency of effect is also made in terms of these three data features, while also including the study of the consistency of an immediate effect (if expected). The summary measures are represented as points on a modified Brinley plot and their similarity is assessed via quantifications of distance. Both absolute and relative measures of consistency are proposed: the former expressed in the same measurement units as the outcome variable and the latter as a percentage. Illustrations with real data sets (multiple baseline, ABAB, and alternating treatments designs) show the wide applicability of the proposals. We developed a user-friendly website to offer both the graphical representations and the quantifications.

The Potential of a Relational Training Intervention to Improve Older Adults' Cognition

Behavioral gerontology rarely focuses on improving older adults' cognitive function. This gap in the literature should be addressed, as our aging population means that greater numbers of older adults are experiencing cognitive decline and reduced functional independence. If cognitive training interventions are to be socially significant, they should target improvements in core executive functions (EFs) that are critical for everyday cognition and functioning independence. Evidence from the cognitive sciences suggests that a cognitive training intervention targeting "relational knowledge" and "cognitive flexibility," which are core EFs, could translate to improvements in cognition and functioning for older adults. Behavioral researchers, interested in the effects of relational training on cognition, have shown a relationship between complex and flexible arbitrarily applicable relational responding (AARRing) and improved performance on measures of intelligence in children and young adults. However, data examining the impact of AARRing on the cognition of older adults are lacking. This article suggests that complex and flexible AARRing may be synonymous with the aforementioned EFs of relational knowledge and cognitive flexibility, and that a behaviorally oriented relational training intervention might improve cognition and functioning for healthy older adults or those experiencing cognitive decline. The article initially presents a brief overview of research in behavioral gerontology and older adult cognition, followed by a detailed explanation of how training complexity and flexibility in AARRing could result in improvements in core EFs. Specific suggestions for designing a relational training intervention and assessing relevant outcomes are provided.

Effects of Intensive Voice Treatment (The Lee Silverman Voice Treatment [LSVT LOUD]) in Subjects With Multiple Sclerosis: A Pilot Study

AIM

The rehabilitation of voice disorders is an unmet need in multiple sclerosis (MS). The Lee Silverman Voice Treatment (LSVT LOUD) is a well-documented and effective speech treatment, developed to treat voice disorders in Parkinson Disease. The purpose of the present study was to examine the viability of applying the LSVT LOUD to individuals with MS and verify short- and long-term improvements in acoustic and perceptual voice parameters.

METHODS

A single subject design was performed in a consecutive sample of 8 subjects with MS. The subjects' voice was recorded with PRAAT software for 5 days at baseline during the 16  treatment sessions, and at follow-up (FU) 6/12 months later. PRAAT provided data on sustained /a/ (SPL/a/) voice intensity and maximum phonation time (MPT/a/) of sustained /a/, and on functional sentences voice intensity. In addition, self-assessment questionnaire Voice Handicap Index, the perceptual GIRBAS scale and intensity of monologue were collected at first day of baseline, post-treatment and at FU. In the treatment phase each subject received treatment according to LSVT LOUD protocol. Visual analysis calculated for daily acoustic variables was used to determine baseline stability and analyse changes following treatment. The Wilcoxon test was used to assess statistically significant differences between baseline and post treatment.

RESULTS

All participants completed the LSVT LOUD programme; one participant dropped out at FU. Improvements in acoustic analysis were found: SPL/a/ improved on average (± standard deviation) 11.64 ± 4.19 dB with 7 subjects showing statistically significant improvement (P < 0.05); MPT/a/ improved on average 1.2 ± 1.53seconds, while intensity of functional sentences improved on average 8.11 ± 3.46  dB with 4 and 5 subjects showed statistically significant improvement, respectively. Intensity of monologue improved 14.90 ± 3.33 dB. Acoustic values are maintained or increased at FU respect to baseline. All subjects improved perceptual ratings at Voice Handicap Index and results were maintained at FU. These changes were associated with improvements on five parameters on the GIRBAS scale at post-treatment, however no further improvement were observed at FU.

CONCLUSION

Intensive LSVT LOUD treatment is a viable approach to treat hypophonia in MS. LSVT LOUD improved both quantitative-instrumental and perceptive-subjective assessments. Randomised controlled trials are needed to provide a firm support on the effectiveness of LSVT LOUD in MS.

The utility of the single-subject method for comparison of temporal-spatial gait changes between a microprocessor and non-microprocessor prosthetic knees

BACKGROUND

Despite increasing knowledge about the potential benefits of advanced user-controlled technology, the decision about switching an individual prosthesis user from a non-microprocessor prosthetic knee to a microprocessor prosthetic knee is mainly based on clinician's experience rather than empirical evidence.

OBJECTIVES

To demonstrate the utility of single-subject design and data analysis for evaluating changes in temporal-spatial gait characteristics between walking with a non-microprocessor prosthetic knee and microprocessor prosthetic knee.

STUDY DESIGN

Single-subject ABA/BAB design.

METHODS

Seven non-microprocessor prosthetic knee users (all men, age 50-84 years, 3-40 years post-amputation) were transitioned through the ABA or BAB phases (A-NMPK, B-MPK, 5 weeks each). Four weekly gait evaluations were performed at three self-selected speeds with an electronic walkway. The non-microprocessor prosthetic knee-microprocessor prosthetic knee differences in stride length-cadence relationship, prosthetic weight acceptance, single-limb support, and step width were evaluated for each subject using the "non-overlap of all pairs" statistical method.

RESULTS

Most subjects improved temporal-spatial gait while on the microprocessor prosthetic knee; in only one subject, none of the 10 gait parameters were in favor of the microprocessor prosthetic knee. In the BAB group, longer use of the microprocessor prosthetic knee was associated with shorter prosthetic weight acceptance and longer single-limb support times across three speeds. Step width either improved with the microprocessor prosthetic knee or remained unchanged in most subjects.

CONCLUSION

The evidence of individual subject improvements in gait coordination, greater reliance on the prosthetic side, and better stability with the microprocessor prosthetic knee than non-microprocessor prosthetic knee over a range of walking speeds demonstrate the practical utility of the single-subject method in clinical decision-making.

CLINICAL RELEVANCE

The results demonstrate the use of the single-subject method for examining person-specific differences in temporal-spatial gait characteristics between walking with a non-microprocessor prosthetic knee and microprocessor prosthetic knee at three self-selected speeds. The method proved feasible and reliable for documenting changes in gait at the individual level, which is relevant for clinical practice.

Effect of Impairment-Oriented and Function-Oriented Exercises on Mouth Function in Subjects with Systemic Sclerosis

PURPOSE

The aim of this study was to develop an exercise protocol to improve maximal mouth opening (MMO), tongue protrusion (Tprot), tongue strength (Tstren), and lip strength (Lstren), and to assess its effects on subjects with scleroderma.

METHODS

We performed four replicated single-system studies in a consecutive sample of subjects with scleroderma. An instrumented assessment measured MMO, Tprot, Tstren, and Lstren. Each day, subjects were assessed and performed orofacial exercises conducted by speech therapists. Treatments were first aimed at improving mouth physical characteristics by impairment-oriented exercises and then to improve skills with function-oriented exercises.

RESULTS

The mean phase differences between assessment and treatment phases across subjects were from 0.88 to 9.56 mm in MMO, from 2.03 to 12.3 mm in Tprot, from -0.12 to 5.35 N in Tstren, and from -0.84 to 5.19 N in Lstren. After treatment, 3 subjects crossed the 5th percentile discriminating normal from abnormal performances for both Tstren and Tprot, while this occurred in 2 subjects for MMO and Lstren.

CONCLUSIONS

The results of this study suggest that rehabilitation appears to be useful in reducing tongue and lip impairments and in improving oral functions in subjects with scleroderma.

Testing Mediators of Youth Intervention Outcomes Using Single-Case Experimental Designs

The major aim of this manuscript is to bring together two important topics that have recently received much attention in child and adolescent research, albeit separately from each other: single-case experimental designs and statistical mediation analysis. Single-case experimental designs (SCEDs) are increasingly recognized as a valuable alternative for Randomized Controlled Trials (RCTs) to test intervention effects in youth populations. Statistical mediation analysis helps provide understanding about the most potent mechanisms of change underlying youth intervention outcomes. In this manuscript we: (i) describe the conceptual framework and outline desiderata for methods for mediation analysis in SCEDs; (ii) describe the main aspects of several data-analytic techniques potentially useful to test mediation in SCEDs; (iii) apply these methods to a single-case treatment data set from one clinically anxious client; and (iv) discuss pros and cons of these methods for testing mediation in SCEDs, and provide future directions.

Evaluating the effectiveness of therapeutic horse riding for children and young people experiencing disability: a single-case experimental design study

Purpose: Therapeutic horse riding aims to improve the health of children and young people experiencing disability; however, its benefits across a range of health domains, particularly the impact on participation outcomes, are not well known. This research evaluated to what extent there was a change in riders balance, functional performance, social responsiveness, quality of life and participation outcomes as a result of therapeutic horse riding.Methods: A multiple-baseline across participants (n = 12) single-case experimental design, with randomly allocated baseline phase lengths, quantitatively evaluated how riders responded to a 20-week intervention.Results: Social participation outcomes measured using the Canadian Occupational Performance Measure demonstrated the most consistent positive between-phase differences (performance ES = 1.20, 95% CI [0.82, 1.63]; satisfaction ES = 1.11, 95% CI [0.73, 1.55]). A causal relationship was seen in three riders, but improvements only reached clinical significance for two riders when accounting for phase data trends. No significant outcome patterns were found comparing riders with principally physical impairments to those with principally psychosocial impairments.Conclusions: Being involved in therapeutic horse riding may improve rider's social participation in home, school and community settings. We postulate that rider self-concept development may be a mechanism of treatment effect leading to participation-level changes.Implications for rehabilitationSocial participation was the health outcome demonstrating the most consistent change following therapeutic horse riding, regardless of rider impairment.Therapeutic horse riding can improve social participation in settings beyond the riding arena.Greater intervention tailoring based on rider responses may enhance therapeutic horse riding intervention effects.

Single-Case Design, Analysis, and Quality Assessment for Intervention Research

BACKGROUND AND PURPOSE

The purpose of this article is to describe single-case studies and contrast them with case studies and randomized clinical trials. We highlight current research designs, analysis techniques, and quality appraisal tools relevant for single-case rehabilitation research.

SUMMARY OF KEY POINTS

Single-case studies can provide a viable alternative to large group studies such as randomized clinical trials. Single-case studies involve repeated measures and manipulation of an independent variable. They can be designed to have strong internal validity for assessing causal relationships between interventions and outcomes, as well as external validity for generalizability of results, particularly when the study designs incorporate replication, randomization, and multiple participants. Single-case studies should not be confused with case studies/series (ie, case reports), which are reports of clinical management of a patient or a small series of patients.

RECOMMENDATIONS FOR CLINICAL PRACTICE

When rigorously designed, single-case studies can be particularly useful experimental designs in a variety of situations, such as when research resources are limited, studied conditions have low incidences, or when examining effects of novel or expensive interventions. Readers will be directed to examples from the published literature in which these techniques have been discussed, evaluated for quality, and implemented.

Applying the Generalized Logistic Model in Single Case Designs: Modeling Treatment-Induced Shifts

Many analytical approaches to single-case data assume either linear effects (regression-based methods) or instant effects (mean-based methods). Neither assumption is realistic; therefore, these approaches’ assumptions are often violated. In this article, we propose modeling curvilinear effects to appropriately parametrize the characteristics of singe-case data. Specifically, we introduce the generalized logistic function as adequate function for this situation. The merits of the proposed procedure are demonstrated using data previously used in single case research that represent typical single case data. We provide the function with auxiliary graphical options to demonstrate the model parameters. The function is freely available in the R package “userfriendlyscience.” The proposed procedure is a new way to analyze single case data, which may provide applied single case researchers with a new tool to better understand their data and avoid applying methods with violated assumptions.

Results reporting in single case experiments and single case meta-analysis

Single Case Experimental Design is a discipline grounded in applied behavior analysis where the needs of individual clients and the application of scientific inquiry are fundamental tenets. These two principles remain tantamount in the conduct of research using this methodology and the expansion of the method into evidence-based practice determinations. Although recommendations for quality indicators are widespread, implementation is not. Concurrent to the rise of quality indicators is an increasing interest in analysis methodology. Visual analysis has a history of application and validity, newer forms of analysis less so. While some argue for concordance between the two, it may be the differences that are worth exploration in understanding characteristics of trend and variability in much of the published literature. Design choice and visual analysis decisions are rarely fully articulated. Statistical analyses are likewise inadequately justified or described. Recommendations for the explicit language of reporting as derived from prior meta-analysis and a current review of two leading journals provides a scaffold consistent with existing guidelines but additive in detail, exemplars, and justification. This is intended to improve reporting of results for individual studies and their potential use in future meta-analytic work.

Single-case experimental designs to assess intervention effectiveness in rehabilitation: A practical guide

Single-case experimental designs (SCED) are experimental designs aiming at testing the effect of an intervention using a small number of patients (typically one to three), using repeated measurements, sequential (±randomized) introduction of an intervention and method-specific data analysis, including visual analysis and specific statistics. The aim of this paper is to familiarise professionals working in different fields of rehabilitation with SCEDs and provide practical advice on how to design and implement a SCED in clinical rehabilitation practice. Research questions suitable for SCEDs and the different types of SCEDs (e.g., alternating treatment designs, introduction/withdrawal designs and multiple baseline designs) are reviewed. Practical steps in preparing a SCED design are outlined. Examples from different rehabilitation domains are provided throughout the paper. Challenging issues such as the choice of the repeated measure, assessment of generalisation, randomization, procedural fidelity, replication and generalizability of findings are discussed. Simple rules and resources for data analysis are presented. The utility of SCEDs in physical and rehabilitation medicine (PRM) are discussed.

One by One: Accumulating Evidence by using Meta-Analytical Procedures for Single-Case Experiments

This paper presents a unilevel and multilevel approach for the analysis and meta-analysis of single-case experiments (SCEs). We propose a definition of SCEs and derive the specific features of SCEs’ data that have to be taken into account when analysing and meta-analysing SCEs. We discuss multilevel models of increasing complexity and propose alternative and complementary techniques based on probability combining and randomisation test wrapping. The proposed techniques are demonstrated with real-life data and corresponding R code.

Analytical Options for Single-Case Experimental Designs: Review and Application to Brain Impairment

Single-case experimental designs meeting evidence standards are useful for identifying empirically-supported practices. Part of the research process entails data analysis, which can be performed both visually and numerically. In the current text, we discuss several statistical techniques focusing on the descriptive quantifications that they provide on aspects such as overlap, difference in level and in slope. In both cases, the numerical results are interpreted in light of the characteristics of the data as identified via visual inspection. Two previously published data sets from patients with traumatic brain injury are re-analysed, illustrating several analytical options and the data patterns for which each of these analytical techniques is especially useful, considering their assumptions and limitations. In order to make the current review maximally informative for applied researchers, we point to free user-friendly web applications of the analytical techniques. Moreover, we offer up-to-date references to the potentially useful analytical techniques not illustrated in the article. Finally, we point to some analytical challenges and offer tentative recommendations about how to deal with them.

Linear Trend in Single-Case Visual and Quantitative Analyses

The frequently used visual analysis of single-case data focuses on data aspects such as level, trend, variability, overlap, immediacy of effect, and consistency of data patterns; most of these aspects are also commonly quantified besides inspecting them visually. The present text focuses on trend, because even linear trend can be operatively defined in several different ways, while there are also different approaches for controlling for baseline trend. We recommend using a quantitative criterion for choosing a trend line fitting technique and comparing baseline and intervention slopes, instead of detrending. We implement our proposal in a free web-based application created specifically for following the What Works Clearinghouse Standards recommendations for visual analysis. This application is especially destined to applied researchers and provides graphical representation of the data, visual aids, and quantifications of the difference between phases in terms of level, trend, and overlap, as well as two quantifications of the immediate effect. An evaluation of the consistency of effects across replications of the AB sequence is also provided. For methodologists and statisticians, we include formulas and examples of the different straight line fitting and detrending techniques to improve the reproducibility of results and simulations.