Bidirectional longitudinal dynamics of self-reported total sleep time and perceived stress: Establishing potential causal relationships.

OBJECTIVE: Most studies in developing countries suggest that less total sleep time (TST) increases subsequent perceived stress (PS) more consistently than the inverse, but have used statistical models that are not optimal when ratings are measured in close proximity. METHODS: We used multilevel dynamic structural equation modeling with Bayesian estimation, ideal for assessing longitudinal daily dynamic interplay between self-reported TST and PS (minimum of 30 days) in 92 Brazilian pre-university students. RESULTS: TST showed lower inertia than PS (autoregressive effect: TST perturbations influenced subsequent TST ratings less so than corresponding PS measures) and exerted negative prospective effects on PS (cross-lagged effect). CONCLUSION: In our developing nation sample, PS deviations from mean ratings took longer to return to baseline values than TST and PS was more sensitive to changes in prior TST than vice-versa, confirming previous findings. Future studies should confirm these findings with objective TST and stress measures.

Reading Comprehension Tests for Children: Test Equating and Specific Age-Interval Reports.

Equating is used to directly compare alternate forms of tests. We describe the equating of two alternative forms of a reading comprehension test for Brazilian children (2nd to 5th grade), Form A (n = 427) and Form B (n = 321). We employed non-equivalent random groups design with internal anchor items. Local independence was attested via standardized residual Pearson's bivariate correlation. First, from 176 items, we selected 42 in each form (33 unique and 9 in common) using 2PL model, a one-dimensional item response theory (IRT) model. Using the equateIRT package for R, the anchor items were used to link both forms. Linking coefficients were estimated under two different methods (Haebara and Stocking-Lord), resulting in scores equating by two methods: observed score equating (OSE) and true score equating (TSE). We provided reference-specific age-intervals for the sample. The final version was informative for a wide range of theta abilities. We concluded that the forms could be used interchangeably.