presents descriptive statistics for the sample, consisting of the mean and standard deviation for each variable. The mean BMI percentile in the sample was 66.2, and in categorical terms (not shown) approximately 19% of the sample was overweight (between the 85th and 95th percentiles), and 16% were obese (≥95th percentile). On average, children played outside about 2 h per day, and watched more than two and a half hours of television per day. Mothers took their children to the playground or the park nearly four times per week. The background characteristics show that the FFCWS sample was relatively disadvantaged (reflecting the urban nature of the sample) with more than one-third of mothers having not completed high school, and the mean income-to-needs ratio was 1.76. In addition, just 32% of mothers were married to the child’s father (or a social father), and 38% were working full-time. Fully 27% of mothers were overweight, and 42% were obese, meaning that nearly three-quarters of the mothers were overweight or obese. Nearly one in five families (19%) lived in public housing, and the mean number of residents per household was 4.63.
Descriptive Statistics for Five-Year Core and In-Home FFCWS Samples
presents results of the OLS analysis designed to validate the association between the physical activity outcomes and children’s BMI. As expected, hours of outdoor play were negatively associated with BMI, and hours of television were positively associated with BMI. For each hour of outdoor play, children, on average, scored about half a percentile point lower on BMI. The corresponding increase for each hour of television was similar, about half a percentile point. Model 3 shows the results when the ratio of outdoor time to television time was included in the model, and results indicate that the higher the ratio of outdoor time to television time on an average weekday, the lower the child’s BMI. In fact, for each additional hour they play outside each day -over and above television watching- children scored 1.5 percentile points lower on BMI. Contrary to expectations, we found that the number of playground trips with the mother per week was not a statistically significant predictor of BMI at age five (although the distribution of this variable was skewed toward the high end). We also found that the income-to-needs ratio was associated in a nonlinear way with BMI percentile, such that it was lowest for the poorest and wealthiest children. Maternal weight status, a very strong predictor of child BMI, captures many of the unobserved factors that correlate with children’s BMI percentiles, and our ability to control for maternal weight is a strength of our study.
OLS Regression of child’s BMI Percentile, Testing Association with Play Outcomes
Our second question focused on the association between neighborhood characteristics and children’s activities. presents results of the negative binomial regression models for hours of outdoor play. In the basic model (Model 1), Black children had an estimated count of outdoor hours of play 18% lower than White children, similar to the result for Hispanic children. Working mothers, and those families interviewed in the winter, reported less time outside. In Model 2 we controlled for residential context, and see that children living in public housing had an estimated outdoor play count 13% higher than other children. Neighborhood poverty was not significantly related to children’s outdoor time, nor was maternal fear about her child playing outdoors.
Negative Binomial Regression Models for Hours of Weekday Outdoor Play
In Model 3, higher levels of collective efficacy were associated with more outdoor play time, even after accounting for differences between neighborhoods in poverty level and other residential context measures. The effect was significant but small; for a standard deviation increase in CE, children’s estimated hours of play increased by 5%. In Model 4, we tested the association between children’s outdoor play and physical disorder in the immediate area around the home, and found that, counter-intuitively, higher physical disorder was associated with more time outdoors for children. This effect was somewhat stronger than the CE effect; a standard deviation increase in physical disorder was associated with a 10% increase in estimated hours of play for children. In a model (not shown) which included both CE and physical disorder (which were correlated _0.19), results were virtually unchanged.
presents results for models examining children’s television time. In Model 1, Black and Hispanic children watched more weekday television, on average, than white children (29% and 16% more, respectively). Similarly, higher-SES children watched less television; each standard deviation increase in the income-to-needs ratio resulted in about 7% less television time. Children of mothers who worked full-time and children enrolled in kindergarten or a daycare program watched less television. Model 2 added the residential context measures, and again we found a significant difference between children who lived in public housing and those who did not -children living in public housing had an 12% increase in the estimated number of hours of television per day. In Model 3, we tested the association between maternal perceptions of collective efficacy and children’s television time, and found that the children of mothers who perceived better collective efficacy in their neighborhoods watched less television. Each standard deviation increase in CE was associated with a 1% decrease in the estimated count of television time for children. We also see that maternal fear of the child playing outside is associated with more television time. Model 4 shows that children living in areas of higher physical disorder watched more television, about 5% more for each standard deviation increase in physical disorder.
Negative Binomial Regression Models for Hours of Weekday Television
Results for the number of times per week the mothers took the children to a park or playground were virtually identical to those for hours of outdoor play, so results are not presented here (available upon request).