A note on using alpha and stratified alpha to estimate the reliability of a test composed of item parcels

Several authors have suggested that prior to conducting a confirmatory factor analysis it may be useful to group items into a smaller number of item ‘parcels’ or ‘testlets’. The present paper mathematically shows that coefficient alpha based on these parcel scores will only exceed alpha based on the entire set of items if W, the ratio of the average covariance of items between parcels to the average covariance of items within parcels, is greater than unity. If W is less than unity, however, and errors of measurement are uncorrelated, then stratified alpha will be a better lower bound to the reliability of a measure than the other two coefficients. Stratified alpha are also equal to the true reliability of a test when items within parcels are essentially tau‐equivalent if one assumes that errors of measurement are not correlated.     

Extracting the Variance Inflation Factor and Other Multicollinearity Diagnostics from Typical Regression Results

Multicollinearity is a potential problem in all regression analyses. However, the examination of multicollinearity is rarely reported in primary studies. In this article we discuss and show several post hoc methods for assessing multicollinearity. One such multicollinearity diagnostic is the variance inflation factor. We outline the post hoc variance inflation factor method, which computes the variance inflation factor from the standardized regression coefficient and semi-partial correlation, both of which can be calculated from commonly reported regression results. Three examples of computing multicollinearity diagnostics using data from published studies are shown. We conclude with a discussion and practical implications.     

Multi-Party,Whole-Body Interactions in Mathematical Activity

This study interrogates the contributions of multi-party, whole-body interactions to students' collaboration and negotiation of mathematics ideas in a task setting called walking scale geometry, where bodies in interaction became complex resources for students' emerging goals in problem solving. Whole bodies took up overlapping roles representing geometric objects, contributing to the communication and negotiation of problem-solving strategies and engaging as mathematical instruments for representation.     

Ethical Challenges for Military Psychologists: When Worlds Collide

Despite the mental health needs in the military and improved access to military psychologists, many in need do not seek psychological services. The military policies, culture, and environment pose considerable barriers to help seeking. In turn, military practices often conflict with the psychologist’s professional ethics, leading to a range of ethical dilemmas including multiple relationships, multiple agencies, and limited confidentiality. To address ethical concerns and encourage service members to seek mental health services, this article proposes maintaining an understanding of military rules, law, and professional ethics; identifying multiple relationships and establishing boundaries up front; and collaborating with the patient in disclosures of information.     

I Can't Wait to Get Married: Gender Differences in Drive to Marry

In this study we examined a new construct—the Drive to Marry (DTM). Young single men and women (149 men and 246 women) rated their desire to get married and completed measures of their valuing of marital, parental, and occupational roles; concern about others' views of them; and feminist attitudes. We found that women had a higher DTM than did men. In both genders, DTM was predicted by the value of parental role and by concern about others' views of them. In women, DTM was also predicted by traditional attitudes toward gender roles, and there was a trend for women who valued the occupational role to have a lower DTM. Conservative women, women who valued the parental role, and women with a higher DTM were also more likely to want to use the title “Mrs.” and to adopt their husband's surname. An earlier version of this paper was presented at the annual meeting of the Midwestern Psychological Association in May 2004.     

Interaction between amount and pattern of training in the induction of intermediate- and long-term memory for sensitization in aplysia

In Aplysia, three distinct phases of memory for sensitization can be dissociated based on their temporal and molecular features. A single training trial induces short-term memory (STM, lasting <30 min), whereas five trials delivered at 15-min intervals induces both intermediate-term memory (ITM, lasting >90 min) and long-term memory (LTM, lasting >24 h). Here, we explore the interaction of amount and pattern of training in establishing ITM and LTM by examining memory for sensitization after different numbers of trials (each trial = one tail shock) and different patterns of training (massed vs. spaced). Under spaced training patterns, two trials produced STM exclusively, whereas four or five trials each produced both ITM and LTM. Three spaced trials failed to induce LTM but did produce an early decaying form of ITM (E-ITM) that was significantly shorter and weaker in magnitude than the late-decaying ITM (L-ITM) observed after four to five trials. In addition, E-ITM was induced after three trials with both massed and spaced patterns of training. However, L-ITM and LTM after four to five trials require spaced training: Four or five massed trials failed to induce LTM and produced only E-ITM. Collectively, our results indicate that in addition to three identified phases of memory for sensitization—STM, ITM, and LTM—a unique temporal profile of memory, E-ITM, is revealed by varying either the amount or pattern of training.