Technical Manual - Renaissance Learning

Reliability and Measurement PrecisionSTAR Early Literacy Enterprise Equivalence Study DataTable 18 presents three different sets of estimates of the STAR Early LiteracyEnterprise measurement error: average conditional standard errors ofmeasurement (CSEM), global standard error of measurement, and retest standarderrors of measurement. Two points should be noted here:1. SEMs calculated using the conditional SEM method probably understatemeasurement error, since they are based on IRT models that do not fit theresponse data perfectly and assume that the IRT item difficulty parametersare estimated without error.2. SEMS calculated using the test-retest score differences probably overstate themeasurement error of a single STAR Early Literacy Enterprise administration,since these estimates are subject to the influence of individual variation overtime, item sampling differences between the initial test and retest, and otherfactors not present in a single administration of the test.All in all, the SEM calculated from the generic reliability coefficients and using thestandard deviation of the observed Scaled Scores may be the best estimate of thetypical SEM for a single test administration. Table 18 provides estimates of thethree SEM calculations for each grade and overall for all grades, Pre-K to Grade 3.Table 18: STAR Early Literacy Enterprise Standard Errors of Measurement from 2014Norming SampleGradeNConditional StandardError of MeasurementAverageCSEMStandardDeviationGlobalStandard ErrorofMeasurementRetestStandard ErrorofMeasurementPre-K 87,800 42.42 13.44 44.5 55.75K 2,376,036 48.81 9.74 49.77 64.691 2,057,861 45.78 10.88 47.05 70.072 553,834 38.55 13.42 40.82 57.323 129,383 34.46 14.34 37.33 55.82All Grades 5,204,914 46.06 11.42 47.45 66.03STAR Early LiteracyTechnical Manual54