Table 3.
District fixed effects regressiona estimates for the relationship between casino slot machines per capitab and 1) body mass index z-score (BMI z score)c and 2) childhood overweight/obesityd among American Indian children, 2001–2012 (n=117 districts and 22,863 observations)
| BMI z score | Percent Overweight/Obesity | ||
|---|---|---|---|
| Beta (95% CI) | Beta (95% CI) | ||
| Change in BMI z score per increase of 1 slot per capita | −0.003*(−0.005, −0.0002) | Absolute change in percentage overweight or obese per increase of 1 slot per capita | −0.19*(−0.26, −0.11) |
| Age (Years) | −0.025*(−0.038, −0.011) | Age (Years) | −1.5*(−2.0, −0.98) |
| Male | 0.010 (−0.022, 0.043) | Male | 0.91 (−0.78, 2.6) |
p-value<0.05
BMI z score: body mass index z-score; CI: Confidence Interval
The statistical models for body mass index z-score were district fixed effects linear regression models; the statistical models for overweight/obesity are district fixed effects linear probability models. In addition to including district fixed effects (i.e. an indicator variable for each district), all models also include indicator variables for each year, an ordered categorical variable for year to provide a linear time trend, and interactions terms between district indicator variables and the linear time trend to allow the trend in BMI z score/obesity to vary by district (coefficients are not shown). All models used robust standard errors that also correct for correlated outcomes within individuals and school districts.20
Casino slot machines per capita was calculated for each school district in every year and represents the number of slot machines per single-race American Indian living on tribal lands within the school district. This number could change over time for each school district, depending on casino opening and expansion dates.
Body Mass Index z-scores were age- and sex-specific using the 2000 Centers for Disease Control (CDC) growth charts
Overweight/obesity was defined as a having a BMI z score ≥85th percentile of the age-and sex-specific 2000 CDC/NCHS Growth Charts14