The purpose of this study is to carry out a content analysis about the studies on teachers' professional development and to determine the tendencies in these studies. Within this scope, 60 studies that were registered to Turkish National Thesis Centre and ProQuest database between the years 2005-2015 were examined. Of the 60 studies, 37 of them…

Educational researchers commonly use the rule of thumb of "design effect smaller than 2" as the justification of not accounting for the multilevel or clustered structure in their data. The rule, however, has not yet been systematically studied in previous research. In the present study, we generated data from three different models…

There are two general methods of cross-validation: empirical estimation, and formula estimation. In choosing a specific cross-validation procedure, one should consider both costs (e.g., inefficient use of available data in estimating regression parameters) and benefits (e.g., accuracy in estimating population cross-validity). Empirical…

Four different procedures were used for estimating the proportion of persons who would be classified consistently as either passing both of two parallel tests or failing both. These four methods were applied at each of four different mastery level scores for each of three different length tests. Data were based on 50 replications of each procedure…

Problems of obtaining a representative sample for a national survey are discussed, and the experiences of Educational Testing Service are used as examples of some methods used to cope with these problems. It is suggested that researchers: (1) capitalize on some existing program; (2) establish in the minds of the possible examinees and the possible…

As in any very large survey, the sample that provided data for the National Longitudinal Study of the High School Class of 1972 (NLS) differed from the random sample of the study design because of nonresponse from 226 of the 1,200 schools in the primary sample, and a small amount of other missing data. Part A of this report, briefly describes the…