The locally best invariant test statistic for testing sphericity of normal distributions is shown to be a simple function of the Box/Geisser - Greenhouse degrees of freedom correction factor in a repeated measures design. Tables of the critical values of the Box/Geiser - Greenhouse correction factor are given. (Author/BW)

Provides an algorithm for determining the median and quartiles of discrete data sets. Describes the graphical equivalent of the numerical method. (JM)

This study compared two approximations for normalizing noncentral F distributions: one based on the square root of the chi-square distribution (SRA), the other derived from a cube root of the chi-square distribution (CRA). The CRA was superior, and generally provided an excellent approximation for noncentral F. (Author/BW)

A sampling subspace in hypothesis testing where Type II error is made for completely illogical reasons from the standpoint of probability is described. The case of unequal probabilities of populations or conditions is also considered. (Author/BS)

Asserts that the inference that a "hump" in the statistical distribution of reading achievement data represents retardation is unwarranted. Contends that the use of any particular cutoff point to identify severe underachievement in reading is arbitrary, and thus that the issue of reading retardation prevalence is inseparable from its definition.…

To satisfy the security requirements of computerized adaptive tests (CATs), efforts have been made to control the exposure rates of optimal items directly by incorporating statistical methods into the item selection procedure. Since differences are likely to occur between the exposure control parameter derivation stage and the operational CAT…

This study compared classical test theory (CTT) and item response theory (IRT). The behavior of the item and person statistics derived from these two measurement frameworks was examined analytically and empirically using a data set obtained from BILOG (R. Mislay and D. Block, 1997). The example was a 15-item test with a sample size of 600…

This study was designed to derive the distribution of a test statistic based on normal probability plots. The first purpose was to provide an empirical derivation of the critical values for the Line Test (LT) with an extensive computer simulation. The goal was to develop a test that is sensitive to a wide range of alternative distributions,…

The use of and emphasis on statistical significance testing has pervaded educational and behavioral research for many decades in spite of criticism by prominent researchers in this field. Much of the controversy is caused by lack of understanding or misinterpretations. This paper reviews criticisms of statistical significance testing and discusses…

A procedure for inferring the validity of a selection test as a predictor of some criterion when the available data are limited due to prior selection is described. (Author/JKS)

Discusses the literature that has become associated with Lotka's Law of Scientific Productivity (a general theoretical estimate of author productivity in the sciences) and attempts to identify the important factors of Lotka's original methodology that should be considered when attempting to test applicability of Lotka's Law. Forty-seven references…

Eight asymptotically robust tests of population correlation coefficient equality are proposed and are studied along with two parametric tests. Monte Carlo simulation is used to compare the small sample performance of these ten procedures. The sampled distributions consist of the normal distribution, two mixed normal distributions and four…

Loyola Law School's plan to normalize grading in sections of a given course involves separate calculations for students with and without statistical background. Examples of class and section distributions are provided, alternative normalization methods are discussed, and the reasons they were not used are noted. (MSE)

Known results for testing and estimation problems for patterned means and covariance matrices with explicit linear maximum likelihood estimates are applied to the block compound symmetry problem. An example involving educational testing is provided. (Author/JKS)

Explains two basic exploratory techniques for displaying and summarizing data--the stem and leaf diagram and the box and whiskers plot--and applies them to a data set consisting of federal allotments and state and local matching funds. One table, three figures, and seven sources are included. (Author/RBF)