Second-order schedules: a comparison of chained, brief-stimulus, and tandem procedures

Pigeons were exposed to seven types of two-component schedules, each component a 2-min fixed-interval schedule. Food presentation occurred at the completion of the second component under all conditions. The seven types of schedules were: (1) a chained schedule in which completion of the first component produced the discriminative stimulus associated with the second component; (2) a chained schedule to which was added the brief presentation of a food-paired stimulus at the completion of the first component; (3) a chained schedule to which was added the brief presentation of a stimulus not paired with food at the completion of the first component; (4) a multiple schedule in which food presentation occurred at the completion of both components; (5) a tandem schedule in which completion of the first component initiated the second component, with no changes in exteroceptive stimuli; (6) a food-paired brief-stimulus schedule in which the brief presentation of a food-paired stimulus was made at the completion of the first component and no other changes in stimuli occurred; and (7) a brief-stimulus schedule in which the brief presentation of a stimulus not paired with food was made at the completion of the first component and no other changes in stimuli occurred. Positively accelerated patterns of responding developed in the first component under three conditions: (1) the chained schedule with the added food-paired brief stimulus; (2) the multiple schedule; and (3) the food-paired brief-stimulus schedule. Response rates were low in the first component, with few instances of positively accelerated patterns, under two conditions: (1) the chained schedule; and (2) the chained schedule with the added nonpaired brief stimulus. The results suggest that a briefly presented food-paired stimulus may function as a more effective conditioned reinforcer than does the presentation of a discriminative stimulus.

The analysis of performance criteria defining course grades as a determinant of college student academic performance

A series of five experimental conditions were designed to investigate the influence of minimum performance criteria and grade labels on college student academic performance. A college course in abnormal psychology was taught in an individualized manner so that each student could perform on each unit of subject matter in individual performance sessions whenever he wished. In each of the five experiments the minimum performance criteria that had to be attained before progressing to the next unit were varied during the quarter and the resulting changes in performance were recorded. In Experiment I there were no criteria; in Experiments II, III, and IV three levels of criteria (High, Medium, and Low) were varied but all of the criteria defined a course grade of "A". In Experiment V, the three criteria defined course grades of A, B, and C. The results showed that the criteria controlled performance to a high degree, so that regardless of what quality of performance had been demonstrated previously or was being produced currently, performance was immediately changed to attain new criteria put into effect. Students in Experiment I produced very poor performance compared to the other conditions.

A parametric analysis of the relationship between food quantity and rumination

Rumination is the chronic regurgitation, chewing, and reswallowing of previously ingested food. The study reported here, using a parametric design, examined the control of rumination by the quantity of food eaten at meals. The subjects were three profoundly retarded individuals who chronically emitted this behavior. The quantity of food by weight ingested daily was varied in 10-oz steps in both ascending and descending series (data were collected only after breakfasts and lunches). Ruminating decreased when food quantity increased and increased when food quantity decreased. In addition, there was a similar inverse interaction between breakfast food quantity and post-lunch ruminating. The data showed relatively rapid transitions in both frequency and duration at each meal size for all subjects. The data establish a clear functional relation between the quantity of food ingested and ruminating.

Continuous versus discrete dimensions of reinforcement schedules: An integrative analysis

An approach to reinforcement-schedule contingencies is presented that accommodates continuous as well as discrete effective dimensions of responses and reinforcers. College students' wheel turning was reinforced by projected reading material according to four schedule contingencies that incorporated either a discontinuous (count) or continuous (duration) dimension of the response and the reinforcer. The contingencies arranged a 1:1 correspondence between (a) response count and consequent stimulus count, (b) response duration and stimulus count, (c) response count and stimulus duration, and (d) response duration and stimulus duration. Contingencies incorporating response count produced moderate to high rates of very short-duration responses. Contingencies incorporating response duration produced very low-rate, long-duration responding. The dimension of the reinforcer had minimal or no additional effect. We suggest that incorporating duration and other continuous dimensions into schedule contingencies may improve our understanding of both laboratory and nonlaboratory behavior.

Modification of consonant speech-sound articulation in young children

A series of three experiments was performed in a classroom setting with small groups of young children with severe articulation problems. Variations on a basic token reinforcement procedure were demonstrated in each experiment. A combined multiple baseline/reversal design showed effective experimenter control of rates of correct and incorrect consonant sound articulation in all cases. In addition, the data in each experiment showed the problems of obtaining stimulus generalization of the high rates of correct articulation to non-training settings. The third experiment demonstrated a procedure for producing such generalization by making each child a discriminative stimulus for correct articulaton by the other child, thus maintaining high levels of correct articulation for each child when in the presence of the other.

A randomised-controlled trial of two educational modes for undergraduate evidence-based medicine learning in Asia

BACKGROUND

As the overall evidence for the effectiveness of teaching of evidence based medicine (EBM) is not strong, and the impact of cultural and societal influences on teaching method is poorly understood, we undertook a randomised-controlled trial to test the effectiveness and learning satisfaction with two different EBM teaching methods (usual teaching vs. problem based learning (PBL)) for undergraduate medical students.

METHODS

A mixed methods study that included a randomised-controlled crossover trial with two intervention arms (usual teaching and PBL) and a nested qualitative study with focus groups to explore student perceptions of learning and to assess the effectiveness and utility of the two teaching methods.All 129 second-year medical students at the University of Hong Kong in 2007.The main outcomes measures were attitudes towards EBM; personal application and current use of EBM; EBM knowledge; future use of EBM.

RESULTS

PBL was less effective at imparting knowledge than usual teaching consisting of a lecture followed by a group tutorial. After usual teaching students showed improvement in scores for 'attitudes towards EBM', 'personal application and current use of EBM' and 'EBM knowledge, which were not evident after PBL. In contrast to the usual teaching, students found PBL difficult as they lacked the statistical knowledge necessary to support discussion, failed to understand core concepts, and lost direction.

CONCLUSION

The evidence presented here would suggest that the teaching of EBM within an Asian environment should adopt a format that facilitates both the acquisition of knowledge and encourages enquiry.

Age-period-cohort analysis of tuberculosis notifications in Hong Kong from 1961 to 2005

BACKGROUND

Despite its wealth, excellent vital indices and robust health care infrastructure, Hong Kong has a relatively high incidence of tuberculosis (TB) (85.4 per 100 000). Hong Kong residents have also experienced a very rapid and recent epidemiological transition; the population largely originated from migration by southern Chinese in the mid 20th century. Given the potentially long latency period of TB infection, an investigation was undertaken to determine the extent to which TB incidence rates reflect the population history and the impact of public health interventions.

METHODS

An age-period-cohort model was used to break down the Hong Kong TB notification rates from 1961 to 2005 into the effects of age, calendar period and birth cohort.

RESULTS

Analysis by age showed a consistent pattern across all the cohorts by year of birth, with a peak in the relative risk of TB at 20-24 years of age. Analysis by year of birth showed an increase in the relative risk of TB from 1880 to 1900, stable risk until 1910, then a linear rate of decline from 1910 with an inflection point at 1990 for a steeper rate of decline. Period effects yielded only one inflection during the calendar years 1971-5.

CONCLUSIONS

Economic development, social change and the World Health Organisation's short-course directly observed therapy (DOTS) strategy have contributed to TB control in Hong Kong. The linear cohort effect until 1990 suggests that a relatively high, but slowly falling, incidence of TB in Hong Kong will continue into the next few decades.

Effectiveness of an elderly smoking cessation counseling training program for social workers: a longitudinal study

BACKGROUND

To achieve greater coverage of the elderly smoking population, the provider/client interface could be broadened to include other professional groups who work with the elderly. We evaluated the effectiveness of a 9-h smoking cessation counseling training program for social workers.

METHODS

We recruited 177 social workers and used a preintervention/postintervention longitudinal design, analyzed by multilevel, multivariable modeling to adjust for between-subjects covariables and within-subjects correlation in repeated measurements at baseline, 3 months, 6 months, and 12 months after training.

RESULTS

Overall, knowledge improved from a mean score of 6.70 +/- 1.03 (+/- SD) at baseline to 7.35 +/- 0.75 at 12 months (range, 0 to 8 correct responses), attitude from 2.84 +/- 0.41 to 3.10 +/- 0.48, and self-perceived competence from 2.49 +/- 0.38 to 2.85 +/- 0.36 (range, 1 to 4, where 4 is best). On multilevel modeling, three of the four "A"s (ask, advice, assist, arrange as per the Agency for Healthcare Research and Quality framework) registered significant gains from baseline to 12 months overall, whereas "advice" did not show any appreciable change.

CONCLUSION

These findings demonstrate that our smoking cessation training program achieved sustained effectiveness in the first year after training in enhancing knowledge, positively shifting attitudes, boosting self-perceived competence, and increasing the self-reported frequency of practicing three of the four As in their routine interaction with elderly clients.

Empirical implications of response acquiescence in discrete-choice contingent valuation

The use of discrete-choice contingent valuation (CV) to elicit individuals' preference, expressed as maximum willingness-to-pay (WTP), although primarily developed in environmental economics, has been popular in the economic evaluation of health and healthcare. However, a concern with this method is the potential for 'over-estimating' WTP values due to the presence of response acquiescence, or 'yea-saying' bias. Based on a CV survey conducted to estimate physicians' valuation of clinic computerization, the extent of such bias was estimated from a within-sample open-ended valuation question following the respondents' discrete choice response. Analysis of this data suggests that not only was response acquiescence an issue, but also that the parametric estimation of mean and median WTP, the most common approach to estimating WTP from discrete-choice data, would potentially magnify such bias (to various degrees depending on the distributional assumptions applied). The possible extent of CV design versus analysis in discrete-choice methods therefore warrants further exploration.

Evidence-based medical education -quo vadis?

The evidence base for most educational initiatives, at least until very recently, is largely composed of low-level evidence. Four major barriers underlie this historical observation, namely: (1) perceived ethical and acceptability problems arising from the unequal treatment of learners in experimental designs; (2) limited choice of outcome measures and validated instruments; (3) time and resource constraints; and (4) methodological issues concerning contextual confounding and small sample sizes. We advocate the adoption of a 'balanced scorecard' approach in the evaluation of education interventions that brings together a comprehensive panel of outcomes under one framework. We require a diversity of rigorously applied methods to generate these outcomes, drawing from the quantitative and qualitative disciplines of epidemiology, psychology and economics. We further suggest that the research community discuss and agree on a standardized set of common metrics or benchmarks. We conclude with a case study examining whether a hand-held computer clinical decision support tool improves clerkship learning of evidence-based medicine. The era of Brownian motion in health education research is over. What we demand in terms of burden of proof for educational effectiveness should be no less rigorous than our call for an ever escalating threshold concerning evidence of clinical care.

Non-attendance and effective equity of access at four public specialist outpatient centers in Hong Kong

This study tests whether socio-economic status (SES), at either the individual or ecologic levels, exerts a direct impact on non-attendance or an indirect impact on attendance through longer waiting time for appointments and/or doctor-shopping behavior at four public specialist outpatient centers in Hong Kong. We collected information through three main sources, namely patients' referral letters, telephone interviews with both open- and closed-ended questions (e.g. doctor-shopping data) and hospital administrative databases from a total of 6495 attenders and non-attenders enrolled from July 2000 through October 2001. Individual-level SES was measured by education, occupation and monthly household income. Tertiary planning unit (TPU)-level SES data consisted of proportion unemployed, proportion with tertiary education, median income and Gini coefficient. Direct effects of SES on non-attendance were examined by logistic regression. Indirect contributions mediated through waiting time and doctor-shopping were analyzed by structural equation modeling. We found that SES, at the individual or ecologic level, did not exert a direct effect on non-attendance. Instead, TPU-level SES contributed positively to waiting time (beta=0.06+/-0.03, p=0.048), i.e. worse-off neighborhoods (and those with greater income inequality) had a shorter waiting time. Individual-level SES was also directly associated with the likelihood of doctor-shopping (beta=0.16+/-0.02, p<0.001), i.e. the poor were less likely to doctor-shop. Both waiting time (beta=0.12+/-0.02, p<0.001) and doctor-shopping (beta=0.37+/-0.02, p<0.001) were significantly related to non-attendance. Our findings suggest a highly equitable specialist ambulatory care public system in Hong Kong. Health care resources are appropriately targeted at the socially indigent, and the poor are not discriminated against and pushed to seek alternative sources of care by the system. These results should be confirmed using a prospective design.

Training nurses and social workers in smoking cessation counseling: a population needs assessment in Hong Kong

BACKGROUND

To achieve greater coverage of elderly smokers and to shift entire populations toward cessation, the provider-client interface could be broadened beyond physicians to include nurses and social workers, who can be formally trained to provide such services. We carried out a population-based training needs assessment of the latter two groups in Hong Kong.

METHODS

Three thousand seven hundred eligible hospital-based nurses and 2,258 social workers who had elderly clients in Hong Kong were recruited in a knowledge, attitude, and practice (KAP) cross-sectional survey. We used multivariable logistic regression to identify predictors for two key outcomes-"initiation and advice" (ask and advise) and "follow-through" (assess, assist and arrange), based on the U.S. Agency for Health Care Policy Research framework.

RESULTS

One thousand eight hundred forty-three (49.8%) nurses and 1,499 (66.4%) social workers responded. Nurses reported a much higher level of engagement in smoking cessation activities than social workers in all five steps of the AHCPR framework (P<0.001). Nurses (mean score=2.99+/-0.40 on a 4-point Likert scale) had more positive attitudes to tobacco control and smoking cessation counseling compared to social workers (mean score=2.79+/-0.41; P<0.001), whereas the latter group perceived themselves as more competent in handling such practice (mean score(nurses)=2.36+/-0.52, mean score(social workers)=2.51+/-0.39; P<0.001). Both attitudinal and self-perceived competence scores predicted incremental gains in the likelihood of offering "follow-through" interventions in addition to those observed for "initiation and advice" actions.

CONCLUSION

Our findings highlight a large degree of unmet need in Hong Kong's hospital-based nurses and social workers who work with the elderly regarding smoking cessation service provision and training. Future research should focus on developing and evaluating programs that encourage nurses and social workers to provide cessation interventions to exert a much greater collective impact than doctors can alone.

Waiting time and doctor shopping in a mixed medical economy

Waiting time generally acts as a rationing mechanism in the public health care system. In theory, patients who have a higher valuation of time are more likely to seek alternative care (i.e. doctor shopping) if there is a parallel private sector than those who have weaker time preference. However, the existing settings of many health care systems do not allow patients to reveal their preference of such. The data presented in this study suggest a positive association between patients' expressed value of time and doctor shopping behaviour in Hong Kong. Patients who were assigned longer waiting times relative to their expected horizon were more likely to seek private alternative care.

Physicians' perceptions towards the impact of and willingness to pay for clinical computerization in Hong Kong

BACKGROUND AND OBJECTIVES

We evaluated factors associated with physicians' perceptions towards the effects of computers on health care and on current levels of computerization in their practice. We also performed a contingent valuation to quantify physicians' perceived benefits from computerization in a hypothetical ambulatory, solo clinic.

METHODS

We surveyed 949 representative physicians in Hong Kong by post. Factor analysis was performed to summarize similar items into categories. Multivariable log-linear regression models were employed to assess the relationships between different factor scores and the number of functions computerized. We elicited their willingness-to-pay (WTP) for three defined computer systems using contingent valuation techniques. WTP values were estimated using econometric modeling by both, parametric and geometric methods. Sociodemographic, attitudinal, and practice-related predictors of WTP were estimated through regression analyses.

RESULTS

Factor analysis revealed a three-factor solution which explained 53% of total variance. The overall mean score (mean = 3.51 +/- 0.45) showed a generally positive attitude towards the effects of computers on health care. Respondents with a higher level of computer knowledge had significantly higher mean overall (P = 0.002) and factor scores for all three factors (P < 0.01). Higher factor scores on the effects of computers on patient care and clinicians (P = 0.006) and on the health system (P = 0.032) were associated with a higher number of functions computerized. The parametric median WTP values for computerizing administrative, clinical, and both sets of functions were HK dollars 21205 (US dollars 2719), HK dollars 34231 (US dollars 4389), and HK dollars 45720 (US dollars 5862), respectively, which were lower than the estimates obtained from demand curves using the geometric method [HK dollars 43286 (US dollars 5549), HK dollars 59570 (US dollars 7637), and HK dollars 84623 (US dollars 10849), respectively]. Doctors with higher incomes were willing to pay more to computerize the clinic, with strong dose-response gradients demonstrated. Those who worked in corporate settings were also more likely to accept higher WTP values.

CONCLUSIONS

Our findings confirm that better knowledge about computers is contributory to a more positive attitude towards the effects of computers on health care, which is in turn significantly associated with higher levels of actual computerization in clinical practice. WTP values represent the likelihood, in monetary terms, of translating doctors' perceived benefits from computerization into investment action.

Do doctors act on their self-reported intention to computerize? A follow-up population-based survey in Hong Kong

BACKGROUND AND OBJECTIVES

We performed a follow-up survey to document changes in the level of computerization among physicians in Hong Kong between 2000 and 2001, specifically examining whether their self-reported intention to computerize various clinical or administrative tasks actually translated into computerization of these tasks 1 year later. Determining such a relationship will indicate the reliability, and thus the utility of questions regarding self-reported intention to computerize clinical practice.

METHODS

A self-completed follow-up postal questionnaire was sent to all 949 physicians who responded to the original questionnaire. Pairwise repeated dichotomous responses from 2000 and 2001 on the computerization of specific functions were compared using McNemar test. Wilcoxon sign-ranked test was employed to compare the total number of tasks computerized in the 2 years. Multivariate logistic regression modeling was carried out to determine predictors for the translation of intention to computerize into actual computerization.

RESULTS

The response rate was 77.0%. There was a significant increase in the number of tasks computerized for both "corporate" and "individual" practices between 2000 and 2001. The proportion of physicians who intended to computerize and actually computerized ranged from 7.7 to 51.0% for different tasks. For five clinical tasks, more than 50% respondents in corporate practices translated the intention to implementation, compared to fewer than 20% in individual practices. Predictors found to be associated with the translation of intention to computerize into actual computerization included higher number of tasks intended to computerize, higher number of tasks already computerized, and more positive physicians' attitudes on the impact of computerization to clinical practice.

CONCLUSIONS

We conclude that physicians' self-reported intention to computerize the clinical practice 12 months previously was moderately associated with actual implementation, with varying degrees of concordance for different clinical and administrative tasks. The identified predictors for the translation of intention to actual computerization may be useful in targeting specific strategies to promote computerization of clinical practice.