Table 3.
Hierarchical models nested within county and state performing the regression of soda, milk and soda:milk price outcomes v. neighbourhood socio-economic status (SES) and the proportion of individuals who are Hispanic or black (n 1743), USA
| Outcome | Estimate | 95 % CI | P value |
|---|---|---|---|
| Neighbourhood SES as the independent variable* | |||
| A. Soda:milk price ratio† | |||
| Unadjusted for covariates‡ | −0·0059 | −0·0087, −0·0030 | <0·0001 |
| Adjusted for race, age, region, urbanicity, supermarket density and TP price§ | −0·0060 | −0·0094, −0·0025 | 0·0006 |
| B. Soda† | |||
| Unadjusted for covariates‡ | 0·0037 | 0·0027, 0·0046 | <0·0001 |
| Adjusted for race, age, region, urbanicity, supermarket density, TP price and milk price§ | 0·0024 | 0·0012, 0·0035 | <0·0001 |
| C. Milk† | |||
| Unadjusted for covariates‡ | 0·0176 | 0·0139, 0·0213 | <0·0001 |
| Adjusted for race, age, region, urbanicity, supermarket density, TP price and soda price§ | 0·0149 | 0·0104, 0·0193 | <0·0001 |
| Race as the independent variable (proportion non-white Hispanic or black)* | |||
| A. Soda:milk price ratio† | |||
| Unadjusted for covariates‡ | −0·0024 | −0·0047, −0·0001 | 0·0384 |
| Adjusted for neighbourhood SES, age, region, urbanicity, supermarket density and TP price§ | −0·0065 | −0·0094, −0·0036 | <0·0001 |
| B. Soda† | |||
| Unadjusted for covariates‡ | −0·0027 | −0·0034, −0·0019 | <0·0001 |
| Adjusted for neighbourhood SES, age, region, urbanicity, supermarket density, TP price and milk price§ | −0·0014 | −0·0023, −0·0004 | 0·0043 |
| C. Milk† | |||
| Unadjusted for covariates‡ | −0·0030 | −0·0060, 0·0000 | 0·0504 |
| Adjusted for neighbourhood SES, age, region, urbanicity, supermarket density, TP price and soda price§ | 0·0072 | 0·0035, 0·0109 | 0·0001 |
TP, toilet paper.
Neighbourhood SES is a standardized variable evaluated as a Z-score; the proportion black/non-white Hispanic is operationalized as an ordinal variable: quintiles cut-offs based on the distribution within the sample.
A negative soda:milk price ratio indicates a larger differential between the two products and may be due to lower soda prices and/or higher milk prices. Soda and milk prices are reported in 2011 US dollar amounts and thus effect estimates can be interpreted as the change in dollars.
While no covariates were included, results are adjusted for county and state via nesting.
Age is the proportion of individuals aged 20 to 39 years, standardized as a Z-score; urbanicity is a categorical variable with values of large metropolitan area (population ≥1 million), small metropolitan area (<1 million), micropolitan area (population 10 000–50 000) and non-core area (population <10 000); supermarket density is an ordinal variable with values from 1 to 4 indicating one to four supermarkets in the census tract area, respectively, and a value of 5 indicating five or more supermarkets.