Table 2.
Difference-in-Difference (DID) Measures Showing Associations Between WIC-participating (Versus Non-participating) Households on Changes in Nutritional Outcomes
| DID early-revision | DID late-revision | |
|---|---|---|
| Nutritional outcome | Mean (95% CI) | Mean (95% CI) |
| Nutrients purchased (capita/day) | ||
| Calories (kcals) | 9.1 (−27.4, 45.6) | −43.4 (−89.7, 2.9) |
| Sodium (mg) | 36.1 (−76.6, 148.9) | −10.8 (−145.5, 123.9) |
| Total fat (g) | 0.3 (−1.3, 1.8) | −1.8 (−3.8, 0.1) |
| Saturated fat (g) | 2.8 (0.4, 5.2) | −0.9 (−3.5, 1.8) |
| Sugar (g) | 1.4 (−1.7, 4.5) | −3.3 (−7.3, 0.6) |
| Protein (g) | 0.4 (−0.8, 1.5) | −0.7 (−2.2, 0.7) |
| Fiber (g) | 0.2 (−0.1, 0.5) | −0.2 (−0.6, 0.2) |
| Select food groups (g/capita/day) | ||
| Breads, rice, tortillas | ||
| Whole grainsa | 1.4 (0.4, 2.4) | −0.2 (−1.3, 1.0) |
| Refined grainsb | −3.0 (−4.6, −1.4) | −4.3 (−6.2, −2.3) |
| Fruits and vegetables (FV) | ||
| FV with no additionsa | −1.1 (−3.5, 1.4) | −0.7 (−3.8, 2.4) |
| FV with added sugar, fats, oils, saltb | −1.3 (−3.2, 0.6) | −0.7 (−3.0, 1.6) |
| Cereals | ||
| Lower-sugara | 0.6 (0.0, 1.2) | 0.6 (−0.1, 1.3) |
| Higher-sugarb | 0.2 (−0.6, 1.0) | −0.1 (−1.1, 0.8) |
| Milk | ||
| Lower-fat milka | 6.5 (−0.8, 13.8) | −0.5 (−9.8, 8.9) |
| Higher-fat milkb | −11.1 (−18.9, −3.3) | −15.9 (−25.7, −6.1) |
| Other beverages | ||
| 100% juicea | 2.1 (−1.3, 5.5) | −1.4 (−5.8, 2.9) |
| Juice drinksb | −0.3 (−4.0, 3.4) | −1.3 (−5.7, 3.2) |
| SSBsb | −4.3 (−19.8, 11.1) | −10.5 (−30.1, 9.1) |
| Dessert, snacks, candy | ||
| Grain based dessertsb | 0.1 (−1.1, 1.3) | 0.0 (−1.5, 1.5) |
| Savory or sweet snacksb | 0.6 (−0.4, 1.7) | 0.3 (−1.0, 1.7) |
| Candyb | 0.1 (−0.7, 0.9) | −0.6 (−1.6, 0.4) |
| Degree of processing or convenience, % | ||
| Processing | ||
| Less | −0.4 (−1.3, 0.5) | −0.9 (−2.1, 0.2) |
| Moderate | 0.5 (−0.1, 1.0) | 0.3 (−0.3, 1.0) |
| High | −0.1 (−1.0, 0.9) | 0.5 (−0.7, 1.7) |
| Convenience | ||
| Ready-to-eat | 0.1 (−0.8, 1.0) | 0.4 (−0.7, 1.5) |
| Ready-to-heat | 0.0 (−0.7, 0.6) | −0.2 (−0.9, 0.6) |
| Requires preparation | −0.2 (−1.0, 0.6) | −0.2 (−1.2, 0.7) |
Source: Authors’ own calculation based in part on data reported by Nielsen through its Homescan Services for all food categories, including beverages and alcohol for the 2008–2014 periods, for the U.S. market (The Nielsen Company, 2015).
Notes: Boldface indicates statistical significance compared to difference between WIC and non-WIC households at pre-revision period, accounting for Bonferroni corrections, at p<0.006.
indicates “WIC Eligible” products meeting WIC nutritional standards based on 7 CFR Part 246.10.
indicates “WIC ineligible” products not meeting WIC nutrition standards. Longitudinal random-effects model covariates include: WIC status, time periods, interactions between WIC status and time-period household composition (number of household members of each age group and sex), education, race/ethnicity of the head of the household, county unemployment rate, state dummies, quarter dummies (to address seasonality in purchases). SEs and CI corrected the SEs with clustering by households.
SSBs, Sugar sweetened beverages; WIC, the Special Supplemental Nutrition Program for Women, Infants, and Children.