An important topic presented in introductory statistics courses is the estimation of population parameters using samples. Students learn that when estimating population variances using sample data, we always get an underestimate of the population variance if we divide by n rather than n-1. One implication of this correction is that the degree of…

Too few researchers understand what statistical significance testing does and does not do, and consequently their results are misinterpreted. This Digest explains the concept of statistical significance testing and discusses the meaning of probabilities, the concept of statistical significance, arguments against significance testing,…

PSYCOM is a unique mixed media package which combines high interest projects on the computer with a written text of expository material. It goes beyond most computer-assisted instruction which emphasizes drill and practice and testing of knowledge. A project might consist of a simulation or an actual experiment, or it might be a demonstration, a…

This manual will familiarize data users with the procedures followed for data collection and processing of the base-year teacher component of the National Education Longitudinal Study of 1988. A corollary objective is to provide the necessary documentation for use of the data files. The manual provides a wide range of information on topics related…

Standards, passing scores, or cut scores have been seen as an element of criterion-referenced tests since their introduction. This paper discusses at least two issues surrounding the establishment of cut scores which appear to need clarification: (1) the theoretical definition of a cut score; and (2) decisions which must be made in selecting a…

the factors which maximize response rates, both through reducing refusals and increasing the probability that respondents will be available for interview, were studied in rural California. Phone directories were used to generate a sample of 250 households who were contacted on either of two evenings or Saturday. The interview questions concerned…

This paper summarizes and highlights some of the critical developments, issues, and trends which impact the work of survey research. The issue of preventing or minimizing nonresponse bias by successfully obtaining cooperation from people being surveyed continues to be of concern to survey research professionals. The most effective response rate…

The discovery of disproportionate minority enrollments in special education classes has been a subject of considerable concern to federal, state, and local education officials alike for the past decade. Because the existence of disproportions is frequently thought to result from discriminatory placement practices on the part of local school…

The sampling errors of maximum likelihood estimates of item-response theory parameters are studied in the case where both people and item parameters are estimated simultaneously. A check on the validity of the standard error formulas is carried out. The effect of varying sample size, test length, and the shape of the ability distribution is…

This report provides information on the background, methodology, and findings of the Videodisc-Microcomputer (ViM) Network project, which brought together over 40 schools in 15 states to explore the potential of a new technology for basic skills instruction. Initiated in 1981 and completed at the end of 1983, the project involved a wide variety of…

An approach was developed based on item-response models defined at the level of salient subject groups rather than at the level of individuals, designed for use with multiple-matrix sampling designs. In each of three National Assessment of Educational Progress (NAEP) mathematics subtopics, Reiser's group-effects latent trait model was fitted to…

Designed as a comprehensive guide to the National Longitudinal Surveys of Labor Market Experience (NLS), this handbook is intended for two major categories of readers. For persons who wish to ascertain whether their research interests can be served by the NLS data, the handbook can provide the detailed description of the objectives of the surveys,…

The statistics in this report are based on data obtained from the October, 1974, Current Population Survey conducted by the Bureau of the Census. Estimates are made of the number of children three to five years old enrolled in preprimary programs and analyzed by selected socioeconomic factors of age, race, type of school, control of school…

In the direct and indirect effects of teacher characteristics on educational production of students over time, this study indicates that teacher characteristics were not critical determinants of student achievement. Characteristics include: experience, educational level, recentness of degree and degree nature, college quality, and other…

Among the variables contributing to the therapeutic relationship between counselor and client, empathy has received much attention in counseling process research. Most of this research has relied on brief segments as a sampling unit; seldom have these segments been compared with entire counseling sessions. Segments of sessions and entire sessions…