# 4.3.2 Sample Balance (re‐interviewed vs. lost treatments)

As noted above, attrition rates in the follow‐up survey were quite high. Of the 743 individuals in the treatment group, only 338 individuals (or about 45%) were successfully re‐contacted and interviewed. This will bias the estimate impacts of the program if changes in youths’ socioeconomic conditions have different effects on the probability that treatments and controls were re‐interviewed. For example, if successful graduates of the program were more likely than successful controls to respond to an interview request, because they felt gratitude towards the program, the benefits of the program could be overstated. Similarly, the benefits of the program could also be overstated if less successful program graduates were less likely to be successfully re‐interviewed because they are ashamed of their current status, or are less favorably disposed to the program.

While the extent of this attrition bias is unobservable, one can gain a measure of insight into the potential for bias by comparing the mean baseline characteristics of participants who were re‐interviewed with those who were not. Similar characteristics among these groups would provide a degree of confidence that observable baseline characteristics, at least, are not systematically related to the probability that participants were successfully re‐interviewed in the follow‐up survey.

The results of this comparison are reported in Table 4B. Column 1 shows results for participants who were not re‐interviewed, Column 2 shows results for participants who were, and FUS, and Column 3 shows the difference. Again, we find that these two groups are very similar in their basic baseline characteristics. They are only slightly different in the mean age, with re‐interviewed treatments being on average 9 months (0.75 years) older, at the time of the baseline, than non‐interviewed treatments. Furthermore, regressions of the main outcomes of interest, measured at baseline, on a dummy for attrition show no significant difference in outcomes at the baseline between the two groups.

To summarize, our results indicate that, in terms of observables, our sample of treatments is a good representation of all youth eligible for the project, and that the treatment group that was successfully re‐ interviewed is very similar to those that were not, in terms of both the baseline basic characteristics and baseline outcomes.

# 4.3.3 Sample Balance (re‐interviewed vs. lost controls)

We next perform the same exercise for controls, comparing the observable baseline characteristics of those who were re‐interviewed with those who were not. The sample of controls consists of 569 individuals, of which 250 (or about 44% of the total sample) were successfully re‐interviewed.<sup>10</sup> The results of this analysis are reported in Table 4 (C). A couple of differences emerge between controls who were re‐contacted and those who were not. In particular, the re‐contacted group contains a statistically

> 10 Note that the original sample of controls is 595 individuals. However, we have missing data for 27 individuals, which results in a sample of 569 individuals for which we report results.

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