This technical report describes the results of analyses performed on data collected from 2013 to 2017, using the IDEA Feedback System for Administrators (FSA). The FSA is used to gather impressions from core constituents about an administrator's performance of relevant administrative roles, as well as her/his leadership style, interpersonal…

Power analysis is a fundamental prerequisite for conducting scientific research. Without power analysis the researcher has no way of knowing whether the sample size is large enough to detect the effect he or she is looking for. This paper demonstrates how psychometric factors such as measurement error and equating error affect the power of…

We investigated methods of including covariates in two-level models for cluster randomized trials to increase power to detect the treatment effect. We compared multilevel models that included either an observed cluster mean or a latent cluster mean as a covariate, as well as the effect of including Level 1 deviation scores in the model. A Monte…

Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This seventh installment of "Explorations in Statistics" explores regression, a technique that estimates the nature of the relationship between two things for which we may only surmise a mechanistic or predictive…

This simulation study examined the performance of the curve-of-factors model (COFM) when autocorrelation and growth processes were present in the first-level factor structure. In addition to the standard curve-of factors growth model, 2 new models were examined: one COFM that included a first-order autoregressive autocorrelation parameter, and a…

Written by a social worker for social work students, this is a nuts and bolts guide to statistics that presents complex calculations and concepts in clear, easy-to-understand language. It includes numerous examples, data sets, and issues that students will encounter in social work practice. The first section introduces basic concepts and terms to…

Several robust absolute deviation statistics have been developed recently. Two such correlation coefficients are developed and discussed, one for ranked data and another for interval level data. The standard error and range of the coefficients are given. The algebraic relationship between the coefficients and three widely used correlation…

The Bologna Declaration brought reforms into higher education that imply changes in teaching methods, didactic materials and textbooks, infrastructures and laboratories, etc. Statistics and mathematics are disciplines that traditionally have the worst success rates, particularly in non-mathematics core curricula courses. This research project,…

Written by an ex-Latin teacher, short-cuts to analyzing test results for the non-mathematical teacher are provided. Discussions are given of item analysis (item analysis by a show of hands, standards for test items: success, standards for test items: discrimination, and the second stage of item analysis. The standard error is then presented (the…

Statistics are an essential tool for making proper judgement decisions. It is concerned with probability distribution models, testing of hypotheses, significance tests and other means of determining the correctness of deductions and the most likely outcome of decisions. Measures of central tendency include the mean, median and mode. A second…

This paper, a revision of the original document, "Correcting Partial, Multiple, and Canonical Correlations for Attenuation" (see TM 000 535), presents the formula for correcting coefficients of partial correlation for attenuation due to errors of measurement. In addition, the correction for attenuation formulas for multiple and cannonical…

In this paper problems caused by the existence of errors of measurement are identified for factor analysis, regression analysis, ANOVA, and ANCOVA. At least one detrimental effect is shown to exist for each type of analysis. When a researcher's interest is with infallible variables, he runs the risk of biased results from all of the procedures…

This self-instructional manual for psychological assessment focuses on the following topics: (1) general statistics, (2) central tendency, (3) random, continuous, and discrete variables, (4) variability, (5) measuring variability, (6) sampling, (7) derived scores, (8) covariation, (9) reliability and validity, and (10) standard error of…

A nontechnical approach to statistics is presented. The examples and illustrations have been drawn from the classroom and the needs of teachers who wish to measure and understand the progress of their pupils. The areas covered include the following topics: (1) different forms of average, middle value, dispersion of data around the average, and the…