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Background. This paper presents reliability and validity analyses of physical activity-related psychosocial questionnaires completed by 8- to 10-year-old African-American girls at baseline and follow-up assessments of pilot intervention studies in the Girls health Enrichment Multi-site Study (GEMS). Methods. Two hundred ten girls participated in the GEMS 12-week pilot studies and had their height and weight measured, wore an accelerometer for 3 days and completed a measure of their usual physical activity (PA) at baseline and after the 12-week intervention. Subgroups of girls also completed physical activity-related psychosocial measures at these two time points including: (a) self-concept; (b) self-efficacy; (c) outcome expectancies; and d) preferences. Principal components analysis was conducted on the psychosocial measures obtained at baseline. Cronbach's alpha and test–retest reliability were computed. Convergent validity was assessed by correlating the baseline psychosocial measures with baseline physical activity measures and body mass index (BMI). Results. The following sub-scales were derived: Activity Preference, Positive Expectancies and Negative Expectancies for physical activity. Physical Performance Self-Concept and Self-Efficacy for physical activity were kept as single dimensional scales. Sub-scales, derived from principal components analyses, were Activity Preference, Positive Expectancies, and Negative Expectancies for physical activity. Internal consistency estimates for the various scales were substantial to excellent (0.67–0.85), while test–retest reliability estimates were fair to moderate (0.22–0.56). Correlations between the PA psychosocial sub-scales and measured levels of activity measures showed evidence of convergent validity for the Activity Preference sub-scale, although social desirability may have influenced the significant associations observed. Conclusions. The Activity Preference was a fairly reliable and valid measure. Further studies are needed to examine the utility of activity-related psychosocial measures in interventions to increase physical activity among preadolescent African-American girls.

Objective. This paper presents the reliability and validity of several diet-related psychosocial questionnaires. Methods. At baseline and 12 weeks follow-up, parents/caregivers of one hundred fifty 8- to 10-year-old African-American completed questionnaires on food preparation habits for their daughter, perceived home barriers to healthy eating, and fruit, juice, vegetable (FJV), low-fat and high-fat food availability. Girls completed a sweetened beverage preferences questionnaire and two 24-h dietary recalls to assess intake. Principal components analyses were conducted for two newly designed measures. Internal consistency was calculated and construct validity was assessed between the psychosocial scales and obesity-related dietary variables. Results. Low-fat and high-fat food preparation for daughters, and perceived home barriers to eating low-fat food and FJV subscales were derived from the new questionnaires. Internal consistency reliabilities were moderate (0.58) to substantial (0.80) across all new and existing scales. Test–retest reliabilities were moderate (0.44) to substantial (0.79). Girls' intake of fat as a percentage of energy was positively related to parental high-fat food preparation for daughters (P < 0.01) and negatively related to parental low-fat food preparation practices for daughters (P < 0.05). Conclusions. Measures of family influences on FJV, fat, and sweetened beverage consumption were internally consistent with moderate to substantial stability. Scales for low-fat and high-fat food preparation practices for daughters achieved construct validity with fat consumption in the hypothesized direction. Family food preparation habits appear to be important targets for future interventions.

Background. Reliability and validity were established for weight concern measures completed by 8–10-year-old African-American girls participating in a pilot obesity prevention program. Methods. Two hundred ten girls and parents participated in the program. Girls completed subscales of the McKnight Risk Factor Survey (MRFS) and body silhouette ratings, had height, weight, and body fat measured, wore accelerometers for 3 days, and completed two dietary recalls. Principal components analysis, internal consistency, and test–retest reliability were computed for weight concerns and body image measures along with convergent validity with body mass index (BMI), percent body fat (PBF), physical activity, and dietary intake. Results. A Moderate Weight Control Behaviors (MWCB) subscale was derived from the MRFS. Overconcern with Weight and Shape (OWS) was a stand-alone scale. Internal consistency estimates for the scales were substantial ranging from 0.71 to 0.84. Test–retest reliabilities were moderate (0.45–0.58). OWS, MWCB, body silhouette rating, and body size discrepancy were positively associated with BMI and PBF. The “like to look” silhouette rating was negatively associated with PBF. Conclusions. Weight concern measures had reasonable levels of internal consistency and promising validity, but only moderate test–retest reliability among preadolescent African-American girls. Refinement and further validation of weight concern measures in this population are warranted.

Background. This study investigated the relationships among optimism, pessimism, physical activity, and dietary behaviors among 8- to 10-year-old African-American girls in the Girls' Health Enrichment Multisite Studies (GEMS). Methods. Ninety-two girls were randomly assigned to a 12-week physical activity and diet intervention or comparison group and completed psychosocial assessments including the Youth Life Orientation Test (YLOT) of optimism and pessimism, physical performance self-concept, physical activity self-efficacy, physical activity outcome expectancies, and physical activity and sedentary preferences. Also, preferences for bottled water and sweetened beverages were assessed. Physical activity and dietary intake were assessed by self-report and parent-report at baseline and follow-up. Also, physical activity was objectively assessed by wearing an accelerometer for 3 days. The psychometric properties of the optimism–pessimism subscales were analyzed. Results. The measures of optimism and pessimism in children were reliable (r = 0.75–0.82). In the multiple regression analyses without the intervention interaction terms, pessimism was positively and significantly related to increases in MET-adjusted usual activity (P = 0.008) and sedentary behaviors (P = 0.0004). Additionally, a negative (P = 0.026) pessimism by intervention interaction term for MET-adjusted usual activity was found such that the intervention group had a lower change in physical activity per unit increase in pessimism compared to the control group. Conclusions: Among 8- to 10-year-old African-American girls, pessimism was related to increased sedentary behaviors and usual activity. Previous studies have reported relationships between optimism and health-compromising behaviors. This study found that pessimism may positively or negatively influence efforts to increase health-promoting behaviors. Future research should confirm and clarify the meaning of these findings.

Background. Measurement enables intervention scientists to determine whether their interventions had the intended outcome effects and the expected pathways of effects across mediating variables. Low reliability of measurement (i.e., substantial random error) attenuates the relationships of these measures to other variables, including treatment effects. This attenuation may indicate that interventions were not effective, when in truth they were. There has been little assessment of the quality of measurement in obesity prevention trials. Method. A brief review is provided of measurement issues within classical test theory. Seventeen obesity prevention trials were then identified in the literature. The extent to which the reliability and validity of the measures were reported in the articles was assessed. Results. With few exceptions reliability coefficients of measures were not reported in the obesity prevention literature. When they were reported, there was evidence that low reliability attenuated reported intervention outcome relationships. Conclusions. The quality of measurement is important in intervention science and consequently should be clearly presented in scientific reports of outcomes. Better measures are needed in obesity prevention to provide appropriate tests of state of the art interventions. A brief overview is provided of each of the articles in this special issue on measurement in the Girls health Enrichment Multisite Studies (GEMS).