Table 3.
Abecedarian Intervention, Males: Health Care at age 30; Physical Development in Childhood. This table presents the inference and descriptive statistics of selected outcomes of the Abecedarian Intervention. The first column describes the outcome analyzed. The remaining six columns present the statistical analysis. The columns present the following information: (1) control mean; (2) treatment mean; (3) unconditional difference in means across treatment and control groups. We multiply the difference in means by (−1) when a higher value of the variable in the raw data represents a worse outcome so that all outcomes are normalized in a favorable direction (but are not restricted to be positive). (4) conditional treatment effect controlling for cohort, number of siblings, mother’s IQ and high-risk index at birth, and accounting for attrition using Inverse Probability Weighting (IPW). The selection of covariates for IPW is based on the lowest Akaike Information Criteria (AIC) among models examining all combinations of covariates that present statistically significant imbalance between attriters and non-attriters. See Supplementary Material Section C and Table S1 for details. (5) one-sided single hypothesis block permutation p-value associated with the IPW treatment effect estimate. By block permutation we mean that permutations are done within strata defined by the pre-program variables used in the randomization protocol: cohort, gender, number of siblings, mother’s IQ, and high-risk index. (6) Multiple Hypothesis stepdown p-values associated with (5). The multiple hypothesis testing is applied to blocks of outcomes. Blocks of variables that are tested jointly using the stepdown algorithm are delineated by horizontal lines. p -values ≤0.10 are in bold type. CDC: Center for Disease Control. WHO: World Health Organization. We use weight-for-length ≥ 85 th percentile for being “at-risk overweight” under 24 months, and BMI-for-age ≥ 85th percentile for being overweight for 24 months and older, see (46). See Table S13 for complete estimation results.
| Variable | Control Mean |
Treatment Mean |
Difference in Means |
Conditional Treatment Effect |
Block p-value |
Step-Down p-value |
|---|---|---|---|---|---|---|
| Health Care at Age 30 | ||||||
| Health Insurance Coverage at age 30 | 0.476 | 0.704 | 0.228 | 0.226 | 0.039 | 0.039 |
| Buys Health Insurance at age 30 | 0.333 | 0.630 | 0.296 | 0.248 | 0.035 | 0.080 |
| Hospital or Doctor Office Care When Sick at age 30 | 0.524 | 0.815 | 0.291 | 0.265 | 0.037 | 0.068 |
| Physical Development in Childhood | ||||||
| At Risk Overweight (CDC) at 3 months | 0.227 | 0.037 | 0.190 | 0.206 | 0.026 | 0.121 |
| At Risk Overweight (CDC) at 6 months | 0.250 | 0.080 | 0.170 | 0.205 | 0.074 | 0.182 |
| At Risk Overweight (CDC) at 9 months | 0.412 | 0.000 | 0.412 | 0.446 | 0.004 | 0.023 |
| At Risk Overweight (CDC) at 12 months | 0.429 | 0.000 | 0.429 | 0.408 | 0.001 | 0.009 |
| At Risk Overweight (CDC) at 18 months | 0.389 | 0.000 | 0.389 | 0.385 | 0.000 | 0.004 |
| Overweight (CDC) at 24 months | 0.333 | 0.000 | 0.333 | 0.343 | 0.001 | 0.011 |
| Overweight (CDC) at 36 months | 0.158 | 0.080 | 0.078 | 0.094 | 0.194 | 0.194 |
| Overweight (CDC) at 48 months | 0.300 | 0.167 | 0.133 | 0.133 | 0.150 | 0.235 |
| Overweight (CDC) at 60 months | 0.300 | 0.125 | 0.175 | 0.187 | 0.058 | 0.179 |
| Overweight (CDC) at 96 months | 0.421 | 0.120 | 0.301 | 0.286 | 0.030 | 0.117 |
| Weight-for-Length Change 0–24 months (CDC) | 0.858 | −0.105 | 0.963 | 1.176 | 0.058 | 0.058 |
| Weight-for-Length Change 0–24 months (WHO) | 1.265 | 0.166 | 1.100 | 1.397 | 0.049 | 0.057 |