Osvaldo F. Morera

The measure of stage of readiness to change : Some psychometric considerations

Previous research in the smoking cessation literature has shown that the key component of the transtheoretical model of change, the stage of readiness to change, is a valid independent measure (C. C. DiClemente & J. O. Prochaska, 1985; C. C. DiClemente et al., 1991; W. F. Velicer, J. S. Rossi, J. O. Prochaska, & C. C. DiClemente, 1996). Recently, however, other health service researchers (e.g., A. J. Farkas et al., 1996b) have begun to question the utility of this model; especially its predictive validity (e.g., A. J. Farkas et al., 1996a). However, no research to date has examined the reliability and stability of the stage of readiness to change measure. In this study, the longitudinal measurement of stage of readiness to change was treated as a quasi-simplex model (K. G. Joreskog, 1970). Estimates of the stability and reliability for 261 female smokers in a general community sample were obtained. Results indicate that the stage of change measure has desirable psychometric properties.

Effectiveness and Spillover of an After-School Health Promotion Program for Hispanic Elementary School Children

OBJECTIVES We evaluated the effectiveness and spillover of an after-school health education and physical activity program among Hispanic elementary school children. METHODS In fall 2008, students in third through fifth grades in 6 schools in El Paso, Texas (n = 901), were randomized to intervention (n = 292 participants) or control (n = 354) classrooms (4 unknown). Intervention classrooms also contained a spillover group (n = 251) that did not join the after-school program but that completed measurements and surveys. The intervention was a 12-week culturally tailored after-school program meeting twice a week. Four-month outcomes were body mass index, aerobic capacity, and dietary intentions and knowledge. We calculated intervention exposure as the proportion of after-school participants per classroom. RESULTS Intervention exposure predicted lower body mass index (P = .045), higher aerobic capacity (P = .012), and greater intentions to eat healthy (P = .046) for the classroom at follow-up. Intervention effectiveness increased with increasing proportions of intervention participants in a classroom. Nonparticipants who had classroom contact with program participants experienced health improvements that could reduce their risk of obesity. CONCLUSIONS Spillover of beneficial intervention effects to nonparticipants is a valuable public health benefit and should be part of program impact assessments.

Changes in self-efficacy and readiness for smoking cessation among women with high school or less education.

The most common theory of smoking cessation postulates that readiness to quit begins with changes in attitudes that move the smoker toward behavioral change and eventual cessation. However, trends in smoking indicate that many who currently smoke are not ready to quit. Hence, strategies that both enhance readiness and focus on quitting are likely to be most effective. We hypothesize that an intervention addressed to motivating behavior change will enhance readiness to change, which will in turn increase the smokers self-efficacy regarding further change. A smoking cessation intervention that combined a self-help booklet and televised segments was developed to address these issues in a population of women smokers with high school or less education. Readiness to quit was measured prior to the intervention, immediately following the intervention, and again at six and 12 months after intervention. The results indicate that the intervention had its effects on readiness to quit, which in turn affected self-efficacy, which further enhanced readiness to quit. These findings indicate that interventions aimed at this group of smokers may need to provide achievable objectives that focus on preparing the smoker to quit as well as promote cessation.

A Confirmatory Factor Analysis of the Attitudes Toward Lesbians and Gay Men (ATLG) Measure

Abstract The Attitudes Toward Lesbians and Gay men (ATLG; Herek, 1988) hypothesizes that individuals can have feelings of sexual prejudice toward gay men and lesbians. No research has confirmed the hypothesized factor structure of the ATLG. This study tested four possible factor structures for the ATLG. Results indicate that the hierarchical factor model provided a good description of the ATLG items. A measure of total sexual prejudice was derived. From the hierarchical structure, a measure representing the difference in sexual prejudice toward gay men and lesbians was also computed. Increased religious involvement and the etiology of homosexuality were statistical predictors of overall sexual prejudice, while decreased religious involvement and gender were statistical predictors of differential sexual prejudice toward gay men.

Disparate WTA–WTP disparities: the influence of human versus natural causes

A host of studies have shown that respondents typically provide larger values reflecting their willingness to accept compensation (WTA) for the loss of a product than amounts they would be willing to pay (WTP) to acquire the same product (Knetsch and Sniden, 1984; Cummings, Brookshire, and Schulze, 1986; Irwin, 1994). Meanwhile, other evidence indicates that causes for the deterioration or the damage of a product (either human or natural) will influence both WTA and WTP (Kahneman et al., 1993; Baron and Ritov, 1992). We conducted two experiments to determine whether human-caused versus naturally occurring events influenced disparities between WTA and WTP values. In the first experiment, residents of a Midwestern city were asked to provide WTA or WTP amounts for the removal of a street tree, either through planned city street widening or because of disease. In the second experiment, students at a large Midwestern university provided WTA and WTP amounts for two environmental scenarios: air quality and the cleanliness of a river. Results of both experiments indicate that the disparity between WTA and WTP is far greater when the damage was caused by humans. Copyright

Assessing Measurement and Predictive Invariance of the Toronto Alexithymia Scale–20 in U.S. Anglo and U.S. Hispanic Student Samples

We collected data from a predominately Anglo American student sample in the Southeastern United States and a predominately Hispanic student sample in the Southwestern United States. Along with an assessment of internal consistency reliability, we examined measurement invariance of the Toronto Alexithymia Scale–20 (TAS–20) using confirmatory factor analysis. We also assessed the predictive invariance of the TAS–20. Results indicate that 2 of the 3 TAS–20 subscales demonstrated satisfactory internal consistency reliability across samples. Items from the TAS–20 subscales demonstrated measurement invariance of the latent means. The relationship between 2 measures of emotional dysfunction and the TAS–20 also demonstrated slope and intercept invariance, indicating equivalent validity.

Important Considerations in Conducting Statistical Mediation Analyses

An investigator wishes to examine mediation in a randomized control trial of the effectiveness of an intervention, which consists of a computerized decision aid for promoting colorectal cancer screening. Mediation is a naturally occurring process, and in any given instance, research investigators seek to ascertain whether it has occurred. In the case of a prevention intervention for a specific chain of events, mediation occurs (1) when the prevention intervention effects a change on a targeted intermediate condition: a mediator, for example, a persons intentions to get a colorectal screening examination; and (2) when, at a later point in time, this condition effects a change on a targeted outcome, for example, the actual behavior of getting a colorectal screening exam. Full mediation is said to occur when the effectiveness of the intervention on the targeted outcome only takes place through the intermediate condition and does not directly affect the targeted outcome. Partial mediation is said to occur when the intervention causes changes in both the intermediate condition and the targeted outcome. The assessment of mediation is important because conclusions about the efficacy of a public health intervention may depend on how these indirect influences are assessed.

The Assessment of Factorial Invariance in Need for Cognition Using Hispanic and Anglo Samples

The Need for Cognition Scale-Short Form (NCS-SF; J. T. Cacioppo, R. E. Petty, & C. F. Kao, 1984) is a commonly administered measure in the behavioral sciences, but little research has assessed its applicability across cultures. A sample of undergraduates in the southeastern United States and a sample of undergraduates at a southwestern U.S. university completed the NCS-SF. Hispanic respondents did not differ from Anglos in their mean NCS-SF scores. Confirmatory factor analysis revealed that factor parameter estimates and item intercepts were partially measurement invariant across samples.

Examining the Effectiveness of a Community-Based Self-Help Program to Increase Women's Readiness for Smoking Cessation

This study investigated the effectiveness of two components of a smoking cessation intervention: a reading manual and a series of televised programs. Female smokers in the Chicago metropolitan area with a high school education or less were interviewed at 4 different times: baseline, immediate postintervention, and 6 and 12 months. We examined the effects of several baseline measures (race, age, number of cigarettes smoked, and stage of readiness to change) and exposure to the intervention components on subsequent stage of change. Race, baseline smoking rate, baseline stage, and exposure to both intervention components had direct effects on stage at immediate postintervention, with both intervention components increasing readiness to quit. Furthermore, exposure to the manual interacted with baseline stage, such that the manual benefited women at earlier stages more than women at later stages. Effects of both components were sustained at 6 months, and the effects of the manual were sustained at 12 months.

Coefficient α as a Measure of Test Score Reliability: Review of 3 Popular Misconceptions

We discuss 3 popular misconceptions about Cronbach α or coefficient α, traditionally used in public health and the behavioral sciences as an index of test score reliability. We also review several other indices of test score reliability. We encourage researchers to thoughtfully consider the nature of their data and the options when choosing an index of reliability, and to clearly communicate this choice and its implications to their audiences.