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Simone A French

Publications and source records attributed to Simone A French.

At least 19 recordsLinked to original sources
PubMed2005

Small-sample performance of the robust score test and its modifications in generalized estimating equations.

The sandwich variance estimator of generalized estimating equations (GEE) may not perform well when the number of independent clusters is small. This could jeopardize the validity of the robust Wald test by causing inflated type I error and lower coverage probability of the corresponding confidence interval than the nominal level. Here, we investigate the small-sample performance of the robust score test for correlated data and propose several modifications to improve the performance. In a simulation study, we compare the robust score test to the robust Wald test for correlated Bernoulli and Poisson data, respectively. It is confirmed that the robust Wald test is too liberal whereas the robust score test is too conservative for small samples. To explain this puzzling operating difference between the two tests, we consider their applications to two special cases, one-sample and two-sample comparisons, thus motivating some modifications to the robust score test. A modification based on a simple adjustment to the usual robust score statistic by a factor of J/(J - 1) (where J is the number of clusters) reduces the conservativeness of the generalized score test. Simulation studies mimicking group-randomized clinical trials with binary and count responses indicated that it may improve the small-sample performance over that of the generalized score and Wald tests with test size closer to the nominal level. Finally, we demonstrate the utility of our proposal by applying it to a group-randomized clinical trial, trying alternative cafeteria options in schools (TACOS).

Adolescent↗
PubMed2005

Perceptions of adolescents involved in promoting lower-fat foods in schools: associations with level of involvement.

This article describes perceptions of adolescents involved in peer-led school-based nutrition promotions encouraging lower-fat food purchases and assesses the differences by level of student involvement. Surveys were administered at schools. Data were collected from 397 high school students from 10 Minnesota schools randomized to the intervention condition of the Trying Alternative Cafeteria Options in Schools study. Students were categorized as highly involved (n=54) or less involved (n=343) based on their level of involvement in promotional activity implementation. Chi 2 tests were conducted to measure the differences between highly-involved and less-involved students in perceptions and attitudes about lower-fat foods. Highly-involved students were significantly more likely than less-involved students to report more healthful eating behaviors and positive attitudes toward lower-fat foods. Student involvement in nutrition interventions should be integrated into programs aimed at increasing healthful food choices among adolescents.

Adolescent↗
PubMed2005

Public health strategies for dietary change: schools and workplaces.

Environmental intervention represents an effective strategy to promote the purchase and consumption of healthful foods in community-based settings. Three such studies promoted the consumption of healthier snacks and lower-fat foods at worksites and at schools. The first study examined lower prices and point-of-purchase promotion on sales of lower-fat snacks in vending machines in 12 worksites and 12 secondary schools. Price reductions of 10%, 25% and 50% on lower-fat snacks resulted in an increase in sales of 9%, 39% and 93%, respectively, as compared to usual-price conditions. The second study examined the impact of a 50% price reduction on the consumption of fresh fruit and baby carrots in 2 secondary school cafeterias. In the third study, 20 secondary schools were randomly assigned to either an environmental intervention or a control group for a 2-y period. The intervention increased the availability of lower-fat foods and implemented student-based promotions. School-based environmental interventions to increase availability and promotion of lower-fat foods and healthier snacks can increase purchase of these foods among adolescents.

Adolescent↗
PubMed2004

Predictors of vigorous exercise adoption and maintenance over four years in a community sample.

BACKGROUND: Very little is known about the correlates of adoption and maintenance of vigorous exercise. The purpose of this study was to understand the sociodemographic correlates of exercise adoption and maintenance in a community sample. METHODS: 917 women and 229 men completed annual surveys as part of a community-based weight gain prevention trial over four years. Multivariate regressions evaluated predictive factors for maintenance of vigorous exercise over time in regular exercisers, and predictors of adoption of exercise in adults who were sedentary at baseline. RESULTS: Exercise maintenance at Years 2 and 3 was associated with ethnicity and exercise level at baseline, while exercise maintenance at Year 4 was associated with television watching, BMI and exercise at baseline. Exercise level at baseline was associated with exercise initiation at Year 2 and Year 3. Income level, marital status, and smoking status predicted exercise initiation at Year 4. CONCLUSIONS: Predictors of vigorous exercise maintenance were more consistent than predictors of vigorous exercise initiation. Results suggest that those who adopt vigorous exercise are a heterogeneous group and intervention messages could be more broadly focused. These data also suggest that exercise maintenance interventions should continue to target low-income populations with messages regarding smoking, weight and television. Clearly further research is needed to understand the factors that contribute to exercise initiation and maintenance, and to develop effective interventions to improve levels of physical activity levels.

Journal Article↗
PubMed2004

Bone outcomes and technical measurement issues of bone health among children and adolescents: considerations for nutrition and physical activity intervention trials.

Weight-bearing physical activity and calcium intake are two important behavioral influences for bone health. Physical-activity and calcium-intake intervention trials with youth have been implemented to evaluate their efficacy and effectiveness to decrease the risk for subsequent osteoporosis and fractures. Technical aspects of bone measurement have not been routinely reported in published trials of youth, even though they can have an impact on study findings and interpretation. This paper provides an overview of the outcome variables reported, and technical issues--such as software and bone detection, growth, and movement--that affect bone mass measurements among children and adolescents. It describes the implications of these issues for the interpretation of intervention effects observed in intervention trials, and provides recommendations for future research.

Absorptiometry, Photon↗
PubMed2004

Adolescents' attitudes about and consumption of low-fat foods: associations with sex and weight-control behaviors.

The objective of the study was to examine adolescents' attitudes about and consumption of low-fat foods by sex and weight-control behaviors. Ninth- to 12th-grade students (n=1,083) in 20 Minnesota high schools completed mail surveys (response rate=74%) as part of baseline measurements (Fall 2001) in a randomized controlled trial (TACOS: Trying Alternative Cafeteria Options in Schools). Linear models examined attitudes and consumption of low-fat foods by sex and weight-control behaviors. Girls were more likely than boys to report positive attitudes and consumption of low-fat foods (all P<.01). Weight-control practices were associated with more positive attitudes about and higher consumption of low-fat foods. Promoting low-fat snacks to adolescents who are interested in weight control may be an effective component of nutrition intervention programs because these students have more positive attitudes about low-fat foods. Dietitians' efforts to educate adolescents about the benefits and healthfulness of low-fat foods would aid intervention programs.

Adolescent↗
PubMed2004

Parental attitudes towards soft drink vending machines in high schools.

Soft drink vending machines are available in 98% of US high schools. However, few data are available about parents' opinions regarding the availability of soft drink vending machines in schools. Six focus groups with 33 parents at three suburban high schools were conducted to describe the perspectives of parents regarding soft drink vending machines in their children's high school. Parents viewed the issue of soft drink vending machines as a matter of their children's personal choice more than as an issue of a healthful school environment. However, parents were unaware of many important details about the soft drink vending machines in their children's school, such as the number and location of machines, hours of operation, types of beverages available, or whether the school had contracts with soft drink companies. Parents need more information about the number of soft drink vending machines at their children's school, the beverages available, the revenue generated by soft drink vending machine sales, and the terms of any contracts between the school and soft drink companies.

Adolescent↗
PubMed2004

School-based research and initiatives: fruit and vegetable environment, policy, and pricing workshop.

BACKGROUND: Foods sold outside the school meals program are widely available and comprise an increasing share of the foods students purchase and consume at school. Federal policies provide little regulation of foods sold outside the school meals program. State and district policies are also limited, and few specifically address fruit and vegetable availability. METHODS: School-based interventions to promote consumption of fruit and vegetables among students in school settings have primarily consisted of multicomponent interventions that sometimes included an environmental intervention component. RESULTS: Results of these interventions have been positive, especially in their effects on fruit intake. The results of shorter term environmental interventions that used lower prices or increased availability as strategies to increase fruit and vegetable intake have been positive. Several new approaches currently being piloted in schools include school gardening programs, salad bars using fresh produce from local Farmer's Markets, and in-school, free fruit and vegetable distribution programs. CONCLUSIONS: Better information is needed on the economics of competitive foods and the role that financial profitability plays in decisions about food availability and sales in the school setting. Although no model programs were identified at the workshop, several promising strategies were identified to promote fruit and vegetable intake among students in school settings.

Feeding Behavior↗
PubMed2004

Weight-bearing physical activity among girls and mothers: relationships to girls' weight status.

OBJECTIVE: To assess weight-bearing physical activity (WBPA) barriers, benefits, self-efficacy, social influence, and behaviors [WBPA and physical activity (PA)] among girls and their mothers according to girls' weight status (nonoverweight vs. overweight). RESEARCH METHODS AND PROCEDURES: Participants were 9- to 11-year-old girls (n = 295) and their mothers who participated in the baseline assessment of a nutrition and PA intervention trial. Girls' and mothers' WBPA attitudes and mothers' WBPA behaviors were self-reported on questionnaires. Girls' WBPA and total PA behaviors were self-reported using a structured interview (Physical Activity Checklist Interview). Stature and weight were measured by standardized anthropometrics. Overweight status was based on BMI. RESULTS: Compared with nonoverweight girls, overweight girls were significantly more likely to report barriers to WBPA participation and perceive social influence from family and friends to do more WBPA. They were also significantly less likely to report self-efficacy regarding WBPA and to believe that they did enough WBPA. Compared with mothers of nonoverweight girls, mothers of overweight girls were significantly more likely to report that it is difficult to persuade their daughters to do more WBPA and significantly less likely to report that WBPA was fun for their daughters. Girls' overweight status was not associated with girls' reports of minutes spent per week in PA or WBPA. DISCUSSION: The present study's findings of lower WBPA self-efficacy, lack of enjoyment of WBPA, and higher perceived social influence to do WBPA among overweight girls suggest that efforts are needed to promote physical competencies and positive perceptions of PA among overweight girls.

Adult↗
PubMed2004

Promotions to increase lower-fat food choices among students in secondary schools: description and outcomes of TACOS (Trying Alternative Cafeteria Options in Schools).

OBJECTIVES: (1) To describe promotional activities, particularly student-led, targeting lower-fat à la carte foods that were conducted in secondary schools; and (2) to describe the relationships between the number and duration of total promotional activities for lower-fat à la carte foods and cafeteria sales of such foods over two years. DESIGN: Promotional activities were implemented in schools that were randomised to the intervention condition of a larger, two-year, school-based, randomised, controlled nutrition intervention trial. SETTING: Ten Minnesota secondary schools. SUBJECTS: Students and school faculty, school food-service and research staff (measured at the school level). RESULTS: Over two years, 181 promotions were implemented (n=49 in Year 1 and n=132 in Year 2). In Year 1, the number of promotions conducted in schools was significantly associated with percentage lower-fat food sales. In Year 2, the duration of promotions was significantly associated with percentage lower-fat food sales. CONCLUSIONS: Collaborative efforts among students, school food-service staff and research staff can be successful in implementing a large number of nutrition-related, school-wide promotional activities. These efforts can increase the sales of lower-fat foods in à la carte areas of school cafeterias.

Adolescent↗
PubMed2004

An environmental intervention to promote lower-fat food choices in secondary schools: outcomes of the TACOS Study.

OBJECTIVES: We evaluated an environmental intervention intended to increase sales of lower-fat foods in secondary school cafeterias. METHODS: Twenty secondary schools were randomly assigned to either an environmental intervention or a control group for a 2-year period. The intervention increased the availability of lower-fat foods and implemented student-based promotions. RESULTS: A steeper rate of increase in sales of lower-fat foods in year 1 (10% intervention vs -2.8% control, P =.002) and a higher percentage of sales of lower-fat foods in year 2 (33.6% intervention vs 22.1% control, P =.04) were observed. There were no significant changes in student self-reported food choices. CONCLUSIONS: School-based environmental interventions to increase availability and promotion of lower-fat foods can increase purchase of these foods among adolescents.

Adolescent↗
PubMed2003

Environmental interventions to promote vegetable and fruit consumption among youth in school settings.

BACKGROUND: This paper reviews the available literature on the school food environment with a focus on identifying effective strategies to promote vegetable and fruit (VF) consumption among youth in school settings. METHODS: Studies were identified through a search of electronic databases as well as references cited within published articles. Seven studies were identified that evaluated changes in VF intake and included a control group. Four additional school-based interventions were reviewed that focused on changes in VF intake as part of a multibehavior intervention. RESULTS: Multicomponent school interventions have been effective in increasing F intake, with reported increases ranging from 0.2 to 0.6 servings per day. Impact on V intake has been less effective, with increases ranging from 0 to 0.3 servings per day. Total VF increases ranged from 0 to 0.6 servings per day. Results of environmental-only, school-based interventions have shown positive effects on students' choice of targeted foods. CONCLUSIONS: Environmental change interventions in schools show potential for positively affecting VF consumption among youth.

Adolescent↗