By converting functional equations to cylindrical coordinates, plotting points on cardboard, and connecting these points with thread, one can make three-dimensional string figures illustrating the behavior of functions for which the derivative is not always defined. (SD)

Presents a description of a relatively new theory which offers a powerful mathematical tool for rigorously synthesizing common theoretical conflicts between discrete and continuous interpretations of scientific phenomena. One particular note is made in reference to man's conceptualization of time. (Author/EB)

The author presents a method of producing a scatter diagram of data on two variables with Pearson product moment correlation of .50; he also provides a proof that the method will work for any number of data pairs. (SD)

The author describes an introduction to, and development of, the complex number field. (SD)

This paper reports an attempt to identify appropriate and robust location estimators for situations that tend to occur among various types of empirical data. Emphasizing robustness across broad unidentifiable ranges of contamination, an attempt was made to replicate, on a somewhat smaller scale, the definitive Princeton Robustness Study of 1972 to…

A brief, practical overview of "design effects" (DEFFs) is presented for users of the results of sample surveys. The overview is intended to help such users to determine how and when to use DEFFs and to compute them correctly. DEFFs are needed only for inferential statistics, not for descriptive statistics. When the selections for…

Determination of the intentions of the test developer is fundamental to the choice of the analytical model for a rating scale. For confirmatory analysis, the developer's intentions inform the choice of the general form of the model, representing the manner in which the respondent interacts with the scale; these intentions also inform the choice of…

A problem that often surfaces in the use of the "t"-test is the absence of critical values for common sample sizes. This problem may cause "guilt" on the part of the professor who must advise students when they encounter discrepancies between their own calculations of the degree of freedom and critical values provided in…

This document describes a mathematical model designed to produce a weighted, standardized index that can be used to represent a statistically unbiased measure of a Future Farmers of America (FFA) chapter's level of activity in relation to other chapters in Ohio. The index, called the FFA Chapter Activity Index, is expected to be applicable to…

A model of test item dependency is presented and used to illustrate the effect that violations of local independence have on the behavior of item characteristic curves. The dependency model is flexible enough to simulate the interaction of a number of factors including item difficulty and item discrimination, varying degrees of item dependence,…

A common problem in practical educational research is that of perfect scores which result when latent trait models are used. A simple procedure for managing the perfect and zero response problem encountered in converting test scores into measures is presented. It allows the test user to chose among two or three reasonable finite representations of…

Growth curve models are a useful tool for developmentalists because they can estimate an attribute's developmental function by providing a mathematical description of growth on an attribute over time. However, selection of a growth curve model appropriate for estimating individual developmental functions is problematic. The ideal model is the one…

A method is described for simultaneous test construction using the Operations Research technique zero-one programming. The model for zero-one programming consists of two parts. The first contains the objective function that describes the aspect to be optimized. The second part contains the constraints under which the objective function should be…