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Johnson, Wendy; Deary, Ian J.; Bouchard, Thomas J., Jr. – Educational and Psychological Measurement, 2018
Most study samples show less variability in key variables than do their source populations due most often to indirect selection into study participation associated with a wide range of personal and circumstantial characteristics. Formulas exist to correct the distortions of population-level correlations created. Formula accuracy has been tested…
Descriptors: Correlation, Sampling, Statistical Distributions, Accuracy
Karoly, Lynn A. – RAND Corporation, 2014
Care Quality Rating and Improvement Systems (QRISs) have advanced and matured, a number of states and localities have undertaken evaluations to validate the systems. Such efforts stem from the desire to ensure that the system is designed and operating in the ways envisioned when the system was established. Given that a central component in a QRIS…
Descriptors: Rating Scales, Program Effectiveness, Early Childhood Education, Educational Quality