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The theoretical reason for the presence of differential item functioning (DIF) is that data are multidimensional and two groups of examinees differ in their underlying ability distribution for the secondary dimension(s). Therefore, the purpose of this study was to determine how much the secondary ability distributions must differ before DIF is detected. Two-dimensional binary data sets were simulated using a compensatory multidimensional item response theory (MIRT) model, incrementally varying the mean difference on the second dimension between reference and focal group examinees while systematically increasing the correlation between dimensions. Three different DIF detection procedures were used to test for DIF: (1) SIBTEST, (2) Mantel-Haenszel, and (3) logistic regression. Results indicated that even with a very small mean difference on the secondary dimension, smaller than typically considered in previous research, DIF will be detected. Additional analyses indicated that even with the smallest mean difference considered in this study, 0.25, statistically significant differences will almost always be found between reference and focal group examinees on subtest scores consisting of items measuring the secondary dimension.

The aim of this study was to investigate the levels of burnout and explore the relationships between burnout and occupational participation among dentists with teaching responsibilities. Canadian Occupational Performance Measure (COPM) was used to evaluate occupational participation with questions on demographic information among 155 dentists with teaching responsibilities. Age, gender, years of experience, academic position were the factors affecting level of burnout and occupational participation. Occupational performance score was negatively correlated with emotional exhausment (r = -.731) and depersonalization (r = -.693) while positively correlated with personal accomplishment (r = .611). Occupational satisfaction scores were negatively correlated with emotional exhausment (r = -.631) and depersonalization (r = -.625) while positively correlated with personal accomplishment (r = .614). Occupational participation level can effect burnout among dentists with teaching responsibilities. Further studies with a larger sample are needed to investigate these preliminary results deeply.

A review of literature covering the past decade indicates a shortage of cluster-randomized trials (CRTs) in education and psychology in Turkey, the gold standard that is capable of producing high-quality evidence for high-stake decision making when individual randomization is not feasible. Scarcity of CRTs is not only detrimental to collective knowledge on the effectiveness of interventions but also hinders efficient design of such studies as prior information is at best incomplete or unavailable. In this illustration, we demonstrate how to estimate variance parameters from existing data and transform them into standardized forms so that they can be used in planning sufficiently powered CRTs. The illustration uses publicly available software and guides researchers step by step via introducing statistical models, defining parameters, relating them to notations in statistical models and power formulas, and estimating variance parameters. Finally, we provide example statistical power and minimum required sample size calculations.