In recent years, computer-based testing (CBT) has grown in popularity, is increasingly being implemented across the United States, and will likely become the primary mode for delivering tests in the future. Although CBT offers many advantages over traditional paper-and-pencil testing, assessment experts, researchers, practitioners, and users have…

To ensure accurate interpretation of research findings, researchers should report details about their research design, data collection method, and response rates when presenting findings from survey research. A review of 100 peer-reviewed articles reporting the results of survey research on K-12 schools with principals as the designated…

This review critically examines the research findings which characterize the cognitive, behavioral, and neuroanatomical features of Williams syndrome (WS). This article analyzes 178 published studies in the WS literature covering the following areas: 1) General intelligence, 2) Language skills, 3) Visuospatial and face processing skills, 4)…

The High School Longitudinal Study of 2009 (HSLS:09) is the fifth in a series of National Center for Education Statistics (NCES) secondary longitudinal studies. The core research questions for HSLS:09 explore secondary to postsecondary transition plans and the evolution of those plans; the paths into and out of science, technology, engineering,…

One of the major problems that a tree-approach to data analysis often encounters is the instability of tree-structures. The instability issue must be dealt with before data can be interpreted by this method. Examining instability at a node of a tree provides insight into the instability of the whole tree, because the same theory of instability…

Whether "more is ever too much" for the number of indicators (p) per factor (p/f) in confirmatory factor analysis (CFA) was studied by varying sample size (N) from 50 to 1,000 and p/f from 2 to 12 items per factor in 30,000 Monte Carlo simulations. For all sample sizes, solution behavior steadily improved (more proper solutions and more…

A sequence of simulations was carried out to aid in the diagnosis and interpretation of equating differences found between random and matched (nonrandom) samples for four commonly used equating procedures: (1) Tucker linear observed-score equating; (2) Levine equally reliable linear observed-score equating; (3) equipercentile curvilinear…

Experimental studies of response rates to mail surveys were reviewed and differences in response by population type were described. Cases were selected for review if they were experimental studies that manipulated a response enhancement factor. Results suggest significant differences in typical response rates for different populations. Higher…

The sampling distribution is a common source of misuse and misunderstanding in the study of statistics. The sampling distribution, underlying distribution, and the Central Limit Theorem are all interconnected in defining and explaining the proper use of the sampling distribution of various statistics. The sampling distribution of a statistic is…

Conventional wisdom suggests the omnibus F-test needs to be significant before conducting post-hoc pairwise multiple comparisons. However, there is little empirical evidence supporting this practice. Protected tests are conducted only after a significant omnibus F-test while unprotected tests are conducted without regard to the significance of the…

Type I error rates were estimated for three tests that compare means by using data from two independent samples: the independent samples t test, Welch's approximate degrees of freedom test, and James's second order test. Type I error rates were estimated for skewed distributions, equal and unequal variances, equal and unequal sample sizes, and a…

As significance testing comes under increasing criticism, some researchers are turning to other indices to evaluate their findings. Included among the alternative options are the interpretation of effect size estimates and the evaluation of sample specificity (invariance testing). Using a hypothetical data set of 64 cases and two predictor…

A specific application of a general paradigm described by R. D. Cook (1986) and R. McCulloch (1985) in assessing local influence is given. Snow geese flock size is estimated as "X" by an observer and "Y" by a photograph. "Y" is believed to be the true flock size. The problem is to obtain true flock size "Z"…

The results of a study of find alternative techniques for testing distributional normality are presented. A group of statistical techniques--some established and some new--were compared using empirical techniques. One new technique which appears to have higher power than the Lilliefors test was subjected to a better definition. Distributions under…

Teacher performance data was used in this investigation to determine whether the stability of variance components and generalizability coefficients could be obtained by increasing sample sizes. A section of the Teacher Performance Assessment Instruments (TPAI) was utilized to assess 2 competencies for each of 750 teachers Each competency, defined…