A General Family of Limited Information Goodness-of-Fit Statistics for Multinomial Data

Maydeu-Olivares and Joe (J. Am. Stat. Assoc. 100:1009–1020, 2005; Psychometrika 71:713–732, 2006) introduced classes of chi-square tests for (sparse) multidimensional multinomial data based on low-order marginal proportions. Our extension provides general conditions under which quadratic forms in linear functions of cell residuals are asymptotically chi-square. The new statistics need not be based on margins, and can be used for one-dimensional multinomials. We also provide theory that explains why limited information statistics have good power, regardless of sparseness. We show how quadratic-form statistics can be constructed that are more powerful than X ² and yet, have approximate chi-square null distribution in finite samples with large models. Examples with models for truncated count data and binary item response data are used to illustrate the theory.     

Control of CRT intensity via Apple II software

An inexpensive, easy-to-build device for the Apple II microprocessor is described. The modification permits software control of four levels of relative screen intensity (contrast) settings for any video monitor. The relationship of the technology to choice reaction time and perception research is briefly indicated. Principles governing operation of the modification are also discussed. Finally, a set of step-by-step instructions for building the device is provided.     

Motivational Systems and Stress-Related Cardiovascular Reactivity

This study examined the relation of motivational systems to patterns of autonomic responses to stress. Specifically, we examined patterns of physiological response resulting from differential activation of motivational systems for behavioral approach and behavioral inhibition. We also examined the relation of these motivational systems to threat and challenge responses to potential stress. Self-report, cardiac measures (i.e., pre-injection period, or PEP, and heart rate, or HR), and blood pressure (i.e., systolic blood pressure, or SBP, and diastolic blood pressure, or DBP) measures reliably distinguished between an experimental condition facilitating behavioral approach and an experimental condition facilitating coactivation of behavioral approach and behavioral inhibition systems. Vascular (e.g., total peripheral resistance, or TPR) and electrodermal (e.g., electrodermal response, or EDR) measures, however, did not vary by condition. We discuss the results in relation to other research on motivational factors as they relate to stress and cardiovascular reactivity.