Assessing the validity of two indirect questioning techniques: A Stochastic Lie Detector versus the Crosswise Model

Prevalence estimates for COVID-19-related health behaviors based on the cheating detection triangular model

BACKGROUND

Survey studies in medical and health sciences predominantly apply a conventional direct questioning (DQ) format to gather private and highly personal information. If the topic under investigation is sensitive or even stigmatizing, such as COVID-19-related health behaviors and adherence to non-pharmaceutical interventions in general, DQ surveys can lead to nonresponse and untruthful answers due to the influence of social desirability bias (SDB). These effects seriously threaten the validity of the results obtained, potentially leading to distorted prevalence estimates for behaviors for which the prevalence in the population is unknown. While this issue cannot be completely avoided, indirect questioning techniques (IQTs) offer a means to mitigate the harmful influence of SDB by guaranteeing the confidentiality of individual responses. The present study aims at assessing the validity of a recently proposed IQT, the Cheating Detection Triangular Model (CDTRM), in estimating the prevalence of COVID-19-related health behaviors while accounting for cheaters who disregard the instructions.

METHODS

In an online survey of 1,714 participants in Taiwan, we obtained CDTRM prevalence estimates via an Expectation-Maximization algorithm for three COVID-19-related health behaviors with different levels of sensitivity. The CDTRM estimates were compared to DQ estimates and to available official statistics provided by the Taiwan Centers for Disease Control. Additionally, the CDTRM allowed us to estimate the share of cheaters who disregarded the instructions and adjust the prevalence estimates for the COVID-19-related health behaviors accordingly.

RESULTS

For a behavior with low sensitivity, CDTRM and DQ estimates were expectedly comparable and in line with official statistics. However, for behaviors with medium and high sensitivity, CDTRM estimates were higher and thus presumably more valid than DQ estimates. Analogously, the estimated cheating rate increased with higher sensitivity of the behavior under study.

CONCLUSIONS

Our findings strongly support the assumption that the CDTRM successfully controlled for the validity-threatening influence of SDB in a survey on three COVID-19-related health behaviors. Consequently, the CDTRM appears to be a promising technique to increase estimation validity compared to conventional DQ for health-related behaviors, and sensitive attributes in general, for which a strong influence of SDB is to be expected.

The analysis of randomized response "ever" and "last year" questions: A non-saturated Multinomial model

Randomized response (RR) is a well-known interview technique designed to eliminate evasive response bias that arises from asking sensitive questions. The most frequently asked questions in RR are either whether respondents were "ever" carriers of the sensitive characteristic, or whether they were carriers in a recent period, for instance, "last year". The present paper proposes a design in which both questions are asked, and derives a multinomial model for the joint analysis of these two questions. Compared to the separate analyses with the binomial model, the model makes a useful distinction between last year and former carriers of the sensitive characteristic, it is more efficient in estimating the prevalence of last year carriers, and it has a degree of freedom that allows for a goodness-of-fit test. Furthermore, it is easily extended to a multinomial logistic regression model to investigate the effects of covariates on the prevalence estimates. These benefits are illustrated in two studies on the use of anabolic androgenic steroids in the Netherlands, one using Kuk and one using both the Kuk and forced response. A salient result of our analyses is that the multinomial model provided ample evidence of response biases in the forced response condition.

Reconstructing individual responses to direct questions: a new method for reconstructing malingered responses

Introduction

The false consensus effect consists of an overestimation of how common a subject opinion is among other people. This research demonstrates that individual endorsement of questions may be predicted by estimating peers' responses to the same question. Moreover, we aim to demonstrate how this prediction can be used to reconstruct the individual's response to a single item as well as the overall response to all of the items, making the technique suitable and effective for malingering detection.

Method

We have validated the procedure of reconstructing individual responses from peers' estimation in two separate studies, one addressing anxiety-related questions and the other to the Dark Triad. The questionnaires, adapted to our scopes, were submitted to the groups of participants for a total of 187 subjects across both studies. Machine learning models were used to estimate the results.

Results

According to the results, individual responses to a single question requiring a "yes" or "no" response are predicted with 70-80% accuracy. The overall participant-predicted score on all questions (total test score) is predicted with a correlation of 0.7-0.77 with actual results.

Discussion

The application of the false consensus effect format is a promising procedure for reconstructing truthful responses in forensic settings when the respondent is highly likely to alter his true (genuine) response and true responses to the tests are missing.

More than random responding: Empirical evidence for the validity of the (Extended) Crosswise Model

The Randomized Response Technique (Warner, Journal of the American Statistical Association, 60, 63-69, 1965) has been developed to control for socially desirable responses in surveys on sensitive attributes. The Crosswise Model (CWM; Yu et al., Metrika, 67, 251-263, 2008) and its extension, the Extended Crosswise Model (ECWM; Heck et al., Behavior Research Methods, 50, 1895-1905, 2018), are advancements of the Randomized Response Technique that have provided promising results in terms of improved validity of the obtained prevalence estimates compared to estimates based on conventional direct questions. However, recent studies have raised the question as to whether these promising results might have been primarily driven by a methodological artifact in terms of random responses rather than a successful control of socially desirable responding. The current study was designed to disentangle the influence of successful control of socially desirable responding and random answer behavior on the validity of (E)CWM estimates. To this end, we orthogonally manipulated the direction of social desirability (undesirable vs. desirable) and the prevalence (high vs. low) of sensitive attributes. Our results generally support the notion that the ECWM successfully controls social desirability bias and is inconsistent with the alternative account that ECWM estimates are distorted by a substantial influence of random responding. The results do not rule out a small proportion of random answers, especially when socially undesirable attributes with high prevalence are studied, or when high randomization probabilities are applied. Our results however do rule out that random responding is a major factor that can account for the findings attesting to the improved validity of (E)CWM as compared with DQ estimates.

Refinement of the extended crosswise model with a number sequence randomizer: Evidence from three different studies in the UK

The Extended Crosswise Model (ECWM) is a randomized response model with neutral response categories, relatively simple instructions, and the availability of a goodness-of-fit test. This paper refines this model with a number sequence randomizer that virtually precludes the possibility to give evasive responses. The motivation for developing this model stems from a strategic priority of WADA (World Anti-Doping Agency) to monitor the prevalence of doping use by elite athletes. For this model we derived a maximum likelihood estimator that allows for binary logistic regression analysis. Three studies were conducted on online platforms with a total of over 6, 000 respondents; two on controlled substance use and one on compliance with COVID-19 regulations in the UK during the first lockdown. The results of these studies are promising. The goodness-of-fit tests showed little to no evidence for response biases, and the ECWM yielded higher prevalence estimates than direct questions for sensitive questions, and similar ones for non-sensitive questions. Furthermore, the randomizer with the shortest number sequences yielded the smallest response error rates on a control question with known prevalence.

Assessing the effectiveness of indirect questioning techniques by detecting liars

In many fields of applied research, mostly in sociological, economic, demographic and medical studies, misreporting due to untruthful responding represents a nonsampling error that frequently occurs especially when survey participants are presented with direct questions about sensitive, highly personal or embarrassing issues. Untruthful responses are likely to affect the overall quality of the collected data and flaw subsequent analyses, including the estimation of salient characteristics of the population under study such as the prevalence of people possessing a sensitive attribute. The problem may be mitigated by adopting indirect questioning techniques which guarantee privacy protection and enhance respondent cooperation. In this paper, making use of direct and indirect questions, we propose a procedure to detect the presence of liars in sensitive surveys which allows researchers to evaluate the impact of untruthful responses on the estimation of the prevalence of a sensitive attribute. We first introduce the theoretical framework, then apply the proposal to the Warner randomized response method, the unrelated question model, the item count technique, the crosswise model and the triangular model. To assess the effectiveness of the procedure, a simulation study is carried out. Finally, the presence and the amount of liars is discussed in two real studies concerning racism and workplace mobbing.

Self-protective and self-sacrificing preferences of pedestrians and passengers in moral dilemmas involving autonomous vehicles

Upon the introduction of autonomous vehicles into daily traffic, it becomes increasingly likely that autonomous vehicles become involved in accident scenarios in which decisions have to be made about how to distribute harm among involved parties. In four experiments, participants made moral decisions from the perspective of a passenger, a pedestrian, or an observer. The results show that the preferred action of an autonomous vehicle strongly depends on perspective. Participants’ judgments reflect self-protective tendencies even when utilitarian motives clearly favor one of the available options. However, with an increasing number of lives at stake, utilitarian preferences increased. In a fifth experiment, we tested whether these results were tainted by social desirability but this was not the case. Overall, the results confirm that strong differences exist among passengers, pedestrians, and observers about the preferred course of action in critical incidents. It is therefore important that the actions of autonomous vehicles are not only oriented towards the needs of their passengers, but also take the interests of other road users into account. Even though utilitarian motives cannot fully reconcile the conflicting interests of passengers and pedestrians, there seem to be some moral preferences that a majority of the participants agree upon regardless of their perspective, including the utilitarian preference to save several other lives over one’s own.

Nothing but the truth? Effects of faking on the validity of the crosswise model

In self-reports, socially desirable responding threatens the validity of prevalence estimates for sensitive personal attitudes and behaviors. Indirect questioning techniques such as the crosswise model attempt to control for the influence of social desirability bias. The crosswise model has repeatedly been found to provide more valid prevalence estimates than direct questions. We investigated whether crosswise model estimates are also less susceptible to deliberate faking than direct questions. To this end, we investigated the effect of "fake good" instructions on responses to direct and crosswise model questions. In a sample of 1,946 university students, 12-month prevalence estimates for a sensitive road traffic behavior were higher and thus presumably more valid in the crosswise model than in a direct question. Moreover, "fake good" instructions severely impaired the validity of the direct questioning estimates, whereas the crosswise model estimates were unaffected by deliberate faking. Participants also reported higher levels of perceived confidentiality and a lower perceived ease of faking in the crosswise model compared to direct questions. Our results corroborate previous studies finding the crosswise model to be an effective tool for counteracting the detrimental effects of positive self-presentation in surveys on sensitive issues.

Functionality of the Crosswise Model for Assessing Sensitive or Transgressive Behavior: A Systematic Review and Meta-Analysis

Tools for reliable assessment of socially sensitive or transgressive behavior warrant constant development. Among them, the Crosswise Model (CM) has gained considerable attention. We systematically reviewed and meta-analyzed empirical applications of CM and addressed a gap for quality assessment of indirect estimation models. Guided by the PRISMA protocol, we identified 45 empirical studies from electronic database and reference searches. Thirty of these were comparative validation studies (CVS) comparing CM and direct question (DQ) estimates. Six prevalence studies exclusively used CM. One was a qualitative study. Behavior investigated were substance use and misuse (k = 13), academic misconduct (k = 8), and corruption, tax evasion, and theft (k = 7) among others. Majority of studies (k = 39) applied the "more is better" hypothesis. Thirty-five studies relied on birthday distribution and 22 of these used P = 0.25 for the non-sensitive item. Overall, 11 studies were assessed as high-, 31 as moderate-, and two as low quality (excluding the qualitative study). The effect of non-compliance was assessed in eight studies. From mixed CVS results, the meta-analysis indicates that CM outperforms DQ on the "more is better" validation criterion, and increasingly so with higher behavior sensitivity. However, little difference was observed between DQ and CM estimates for items with DQ prevalence estimate around 50%. Based on empirical evidence available to date, our study provides support for the superiority of CM to DQ in assessing sensitive/transgressive behavior. Despite some limitations, CM is a valuable and promising tool for population level investigation.

Human-Wildlife Conflict Mitigation Impacts Community Perceptions around Kibale National Park, Uganda

The attitudes of community members living around protected areas are an important and often overlooked consideration for effective conservation strategies. Around Kibale National Park (KNP) in western Uganda, communities regularly face the threat of crop destruction from wildlife, including from a variety of endangered species, such as African elephants (Loxodonta africana), common chimpanzees (Pan troglodytes), and red colobus monkeys (Piliocolobus tephrosceles), as well as other nonhuman primates, including olive baboons (Papio anubis). These frequent negative interactions with wildlife lead many community members to resent the park and the animals that live within it. To mitigate these issues, community members around KNP partnered with researchers to start a participatory action research project to reduce human-wildlife interactions. The project tested four sustainable human-wildlife conflict mitigation strategies: digging and maintaining trenches around the park border, installing beehive fences in swampy areas where trenches could not be dug, planting tea as a buffer, and growing garlic as a cash crop. These physical exclusion methods and agriculture-based deterrents aimed to reduce crop destruction by wild animals and improve conditions for humans and wildlife alike. We conducted oral surveys with members of participating communities and a nonparticipating community that border KNP to determine the impact of these sustainable human-wildlife conflict mitigation strategies on attitudes toward KNP, wildlife officials, and animal species in and around KNP. We found that there is a positive correlation between participation in the project and perceived benefits of living near KNP. We also found that respondents who participated in the project reported more positive feelings about the Uganda Wildlife Authority, the organization that oversees KNP. This research will help inform future conservation initiatives around KNP and other areas where humans and animals face conflict through crop damage.

On the validity of non-randomized response techniques: an experimental comparison of the crosswise model and the triangular model

Non-randomized response techniques (NRRTs) such as the crosswise model and the triangular model (CWM and TRM; Yu et al. Metrika, 67, 251-263, 2008) have been developed to control for socially desirable responding in surveys on sensitive personal attributes. We present the first study to directly compare the validity of the CWM and TRM and contrast their performance with a conventional direct questioning (DQ) approach. In a paper-pencil survey of 1382 students, we obtained prevalence estimates for two sensitive attributes (xenophobia and rejection of further refugee admissions) and one nonsensitive control attribute with a known prevalence (the first letter of respondents' surnames). Both NRRTs yielded descriptively higher prevalence estimates for the sensitive attributes than DQ; however, only the CWM estimates were significantly higher. We attribute the higher prevalence estimates for the CWM to its response symmetry, which is lacking in the TRM. Only the CWM provides symmetric answer options, meaning that there is no "safe" alternative respondents can choose to distance themselves from being carriers of the sensitive attribute. Prevalence estimates for the nonsensitive control attribute with known prevalence confirmed that neither method suffered from method-specific bias towards over- or underestimation. Exploratory moderator analyses further suggested that the sensitive attributes were perceived as more sensitive among politically left-oriented than among politically right-oriented respondents. Based on our results, we recommend using the CWM over the TRM in future studies on sensitive personal attributes.

Controlling social desirability bias: An experimental investigation of the extended crosswise model

Indirect questioning techniques such as the crosswise model aim to control for socially desirable responding in surveys on sensitive personal attributes. Recently, the extended crosswise model has been proposed as an improvement over the original crosswise model. It offers all of the advantages of the original crosswise model while also enabling the detection of systematic response biases. We applied the extended crosswise model to a new sensitive attribute, campus islamophobia, and present the first experimental investigation including an extended crosswise model, and a direct questioning control condition, respectively. In a paper-pencil questionnaire, we surveyed 1,361 German university students using either a direct question or the extended crosswise model. We found that the extended crosswise model provided a good model fit, indicating no systematic response bias and allowing for a pooling of the data of both groups of the extended crosswise model. Moreover, the extended crosswise model yielded significantly higher estimates of campus Islamophobia than a direct question. This result could either indicate that the extended crosswise model was successful in controlling for social desirability, or that response biases such as false positives or careless responding have inflated the estimate, which cannot be decided on the basis of the available data. Our findings highlight the importance of detecting response biases in surveys implementing indirect questioning techniques.

How prevalent is plagiarism among college students? Anonymity preserving evidence from Austrian undergraduates

Plagiarism in academia is endangering the veracity of any discipline. Yet, estimating the actual prevalence of plagiarism is difficult due to the sensitive nature of freely admitting actual offenses. Respondents to questions on plagiarism oftentimes conceal potential misconduct and thus refrain from truthfully responding to such a sensitive question. In this work, we therefore employ item-count techniques to provide a better estimate of the prevalence in academia using a student sample. Our results drawing on 428 students from an Austrian university reveal a high prevalence of plagiarism (around 22 percentage points). We also assess the robustness of the findings using placebo measurements. Our results suggest a much higher prevalence of plagiarism then comparison studies when respondents can be convincingly assured of their anonymity.

Can detailed instructions and comprehension checks increase the validity of crosswise model estimates?

The crosswise model is an indirect questioning technique designed to control for socially desirable responding. Although the technique has delivered promising results in terms of improved validity in survey studies of sensitive issues, recent studies have indicated that the crosswise model may sometimes produce false positives. Hence, we investigated whether an insufficient understanding of the crosswise model instructions might be responsible for these false positives and whether ensuring a deeper understanding of the model and surveying more highly educated respondents reduces the problem of false positives. To this end, we experimentally manipulated the amount of information respondents received in the crosswise model instructions. We compared a crosswise model condition with only brief instructions and a crosswise model condition with detailed instructions and additional comprehension checks. Additionally, we compared the validity of crosswise model estimates between a higher- and a lower-educated subgroup of respondents. Our results indicate that false positives among highly educated respondents can be reduced when detailed instructions and comprehension checks are employed. Since false positives can also occur in direct questioning, they do not appear to be a specific flaw of the crosswise model, but rather a more general problem of self-reports on sensitive topics. False negatives were found to occur for all questioning techniques, but were less prevalent in the crosswise model than in the direct questioning condition. We highlight the importance of comprehension checks when applying indirect questioning and emphasize the necessity of developing instructions suitable for lower-educated respondents.

Symbolic Product Superiority in the Neural Salience of Compensatory Consumption Behavior

To cope with self-threat being induced by personal setbacks in daily life, compensatory consumption, especially on symbolic product, has been found to do valuable help to resolve discrepancies between ideal and actual self-concept. Conforming to symbolic self-completion theory, the current study adopted event-related potentials to explore the objective information processing stages in self-concept-impaired status (the defeat group) on a neural level. The behavioral results replicated previous findings that the defeat group gained stronger purchase intention for symbolic products than utilitarian products. The electrophysiological data demonstrated that perceptual difficulties for products in preliminary stage (N1) were steady among conditions, and after that, information processing separation emerged. In contrast to the individuals with a draw experience, those with a defeat experience raised highly focused attention (P2) and eager expectation (N2) for products, especially for symbolic ones. Meanwhile, symbolic (vs. utilitarian) products also evoked a higher emotional arousal level and slowed the diminishment of involved attentional resource (late positive potential) at late cognitive processing stage. Taken together, the sequential integration of multiple neural indicators contributes to elucidating the processing stages of compensatory consumption behavior.

Asking Survey Questions About Criminal Justice Involvement

Criminal justice involvement is a multifaceted construct encompassing various forms of contact with the criminal justice system. It is a sensitive topic to ask about in surveys and also a sensitive topic for respondents to answer. This article provides guidance for writing survey questions on criminal justice involvement, starting with a review of potential causes for reporting error and nonresponse error associated with survey questions on criminal justice involvement. Questions about criminal justice involvement are subject to errors that are common to any survey (eg, misunderstanding questions, recall bias, telescoping). Reponses to these questions are also subject to underreporting because of social desirability concerns. We also address strategies to reduce error for questions pertaining to criminal justice involvement (eg, self-administered data collection, wording of forgiving questions, indirect methods). We then discuss common design decisions associated with writing survey questions on criminal justice involvement (eg, type and frequency of criminal justice involvement, reference period,) and provide examples of questions from current surveys.

Implementation evaluation of an iron supplementation programme in high-school students: the crosswise model

OBJECTIVE

To evaluate the implementation of the national health promotion programme (through nutritional education and Fe supplementation) among female high-school students in Iran and to assess the application of the crosswise model (CM) for evaluating the programme's implementation.

DESIGN

Two cross-sectional surveys in female high-school students, one using the direct questioning (DQ) method and the other using the CM, were conducted. Two survey questionnaires used to collect the data contained questions about three aspects of the programme: delivering the Fe supplements, consuming them and holding nutritional training sessions.

SETTING

Female high schools, West Azerbaijan Province, Iran.

PARTICIPANTS

A sample of 2180 students, of whom 1740 were surveyed by the CM and 440 were interviewed by DQ.

RESULTS

The CM resulted in estimates that were consistently lower than the estimates of the DQ. The proportion of students in the DQ and CM who reported receiving the pills weekly and on a regular basis was 73·2 and 22·5 %, respectively. About 43 and 31 % of students in the DQ and CM surveys reported consuming all pills delivered to them. In the DQ method, only 12 % of students who reported the number of pills consumed had taken the complete dose (sixteen pills).

CONCLUSIONS

Implementation of the Fe supplementation programme in female high schools was poor and insufficient, so that it seems unsuccessful in reducing Fe-deficiency anaemia in adolescent girls. The CM might be considered for evaluating the health programme's implementation at high schools.

Detecting nonadherence without loss in efficiency: A simple extension of the crosswise model

In surveys concerning sensitive behavior or attitudes, respondents often do not answer truthfully, because of social desirability bias. To elicit more honest responding, the randomized-response (RR) technique aims at increasing perceived and actual anonymity by prompting respondents to answer with a randomly modified and thus uninformative response. In the crosswise model, as a particularly promising variant of the RR, this is achieved by adding a second, nonsensitive question and by prompting respondents to answer both questions jointly. Despite increased privacy protection and empirically higher prevalence estimates of socially undesirable behaviors, evidence also suggests that some respondents might still not adhere to the instructions, in turn leading to questionable results. Herein we propose an extension of the crosswise model (ECWM) that makes it possible to detect several types of response biases with adequate power in realistic sample sizes. Importantly, the ECWM allows for testing the validity of the model's assumptions without any loss in statistical efficiency. Finally, we provide an empirical example supporting the usefulness of the ECWM.

Sensitivity of Crosswise Model to Simplistic Selection of Nonsensitive Questions: An Application to Estimate Substance Use, Alcohol Consumption and Extramarital Sex Among Iranian College Students

BACKGROUND

Nonrandomized response (NRR) models are a new generation of surveys for sensitive issues. This study aims to evaluate the validity of estimates from the crosswise model (as one of the efficient models) through employing different response probabilities of nonsensitive questions.

METHODS

This cross-sectional study was conducted during October and November 2015 among 1777 students of Tabriz University of Medical Sciences. Estimates of monthly alcohol consumption, and at least one instance of illicit drug use and extramarital sex over the last year were determined using direct questioning (DQ) and the Crosswise model (CM). In the last model, the probability of positive response to the nonsensitive questions was determined by using five different methods: uniform distribution (I), Benford's law (II), and estimations based on data from three other studies (III, IV, V).

RESULTS

Crosswise estimates of sensitive behaviors with different probabilities of a positive response to nonsensitive questions differed significantly. For example, estimates of history of using illegal opioids at least once in the last year among men varied significantly from 5.0% to 16.1% with different crosswise models based on the probability of being born in Spring using method I (0.250), III (0.287), IV (0.248), and V (0.310). The model based on Benford's law (II) was applied to estimate alcohol and cannabis consumption, and its estimates showed significant discrepancy with results of crosswise models I and V.

CONCLUSION

Estimates from crosswise model is highly sensitive to the response probability of nonsensitive questions. It seems that if this question is not selected carefully, the mentioned models will provide overestimates or underestimates, and the more-is-better hypothesis is not always valid. To achieve valid estimates, the exact probability of a positive response to the nonsensitive question must be known for the studied population.

More is not always better: An experimental individual-level validation of the randomized response technique and the crosswise model

Social desirability and the fear of sanctions can deter survey respondents from responding truthfully to sensitive questions. Self-reports on norm breaking behavior such as shoplifting, non-voting, or tax evasion may thus be subject to considerable misreporting. To mitigate such response bias, various indirect question techniques, such as the randomized response technique (RRT), have been proposed. We evaluate the viability of several popular variants of the RRT, including the recently proposed crosswise-model RRT, by comparing respondents' self-reports on cheating in dice games to actual cheating behavior, thereby distinguishing between false negatives (underreporting) and false positives (overreporting). The study has been implemented as an online survey on Amazon Mechanical Turk (N = 6, 505). Our results from two validation designs indicate that the forced-response RRT and the unrelated-question RRT, as implemented in our survey, fail to reduce the level of misreporting compared to conventional direct questioning. For the crosswise-model RRT we do observe a reduction of false negatives. At the same time, however, there is a non-ignorable increase in false positives; a flaw that previous evaluation studies relying on comparative or aggregate-level validation could not detect. Overall, none of the evaluated indirect techniques outperformed conventional direct questioning. Furthermore, our study demonstrates the importance of identifying false negatives as well as false positives to avoid false conclusions about the validity of indirect sensitive question techniques.

On the comprehensibility and perceived privacy protection of indirect questioning techniques

On surveys that assess sensitive personal attributes, indirect questioning aims at increasing respondents' willingness to answer truthfully by protecting confidentiality. However, the assumption that subjects understand questioning procedures fully and trust them to protect their privacy is rarely tested. In a scenario-based design, we compared four indirect questioning procedures in terms of their comprehensibility and perceived privacy protection. All indirect questioning techniques were found to be less comprehensible by respondents than a conventional direct question used for comparison. Less-educated respondents experienced more difficulties when confronted with any indirect questioning technique. Regardless of education, the crosswise model was found to be the most comprehensible among the four indirect methods. Indirect questioning in general was perceived to increase privacy protection in comparison to a direct question. Unexpectedly, comprehension and perceived privacy protection did not correlate. We recommend assessing these factors separately in future evaluations of indirect questioning.

Multiple sensitive estimation and optimal sample size allocation in the item sum technique

For surveys of sensitive issues in life sciences, statistical procedures can be used to reduce nonresponse and social desirability response bias. Both of these phenomena provoke nonsampling errors that are difficult to deal with and can seriously flaw the validity of the analyses. The item sum technique (IST) is a very recent indirect questioning method derived from the item count technique that seeks to procure more reliable responses on quantitative items than direct questioning while preserving respondents' anonymity. This article addresses two important questions concerning the IST: (i) its implementation when two or more sensitive variables are investigated and efficient estimates of their unknown population means are required; (ii) the determination of the optimal sample size to achieve minimum variance estimates. These aspects are of great relevance for survey practitioners engaged in sensitive research and, to the best of our knowledge, were not studied so far. In this article, theoretical results for multiple estimation and optimal allocation are obtained under a generic sampling design and then particularized to simple random sampling and stratified sampling designs. Theoretical considerations are integrated with a number of simulation studies based on data from two real surveys and conducted to ascertain the efficiency gain derived from optimal allocation in different situations. One of the surveys concerns cannabis consumption among university students. Our findings highlight some methodological advances that can be obtained in life sciences IST surveys when optimal allocation is achieved.

A Strong Validation of the Crosswise Model Using Experimentally-Induced Cheating Behavior

We constructed an online cheating paradigm that could be used to validate the Crosswise Model ( Yu, Tian, & Tang, 2008 ), a promising indirect questioning technique designed to control for socially desirable responding on sensitive questions. Participants qualified for a reward only if they could identify the target words from three anagrams, one of which was virtually unsolvable as shown on a pretest. Of the 664 participants, 15.5% overreported their performance and were categorized as cheaters. When participants were asked to report whether they had cheated, a conventional direct question resulted in a substantial underestimate (5.1%) of the known prevalence of cheaters. Using a CWM question resulted in a more accurate estimate (13.0%). This result shows that the CWM can be used to control for socially desirable responding and provides estimates that are much closer to the known prevalence of a sensitive personal attribute than those obtained using a direct question.