APPENDIX: EVALUATION DESIGN AND DATA COLLECTION

We made an attempt to interview both program participants and comparison group members three times over a six-year period, 1990-1995 (see Table 19). We were able to successfully interview 129 of the original 153 program entrants, a response rate of 84 percent; 54 of the 71 comparison group members, a response rate of 76 percent, were interviewed at least once. The first interview included retrospective questions, allowing those who were interviewed only once to be included in some longitudinal analyses.

Table 19: Numbers of Interviews in Each Wave

Numbers in parentheses indicate proportion of population surveyed.

Some attrition in the panel study occurred. Not everyone was interviewed in all three waves of the study. We were able to interview 61 percent of the 54 comparison group members and 41 percent of the 128 program participants three times (see Table 20). Another 26 percent of the comparison group and 30 percent of program participants had two interviews. Thus, if we combine the proportions of the two groups that had two and three interviews, we had 87 percent of the comparison group and 71 percent of program participants that took part in at least two interviews. A mere 13 percent of the comparison group and 28 percent of program participants had only one interview.

Table 20: Cases with One, Two, and Three Interviews

Numbers in parentheses indicate the proportion of interviews with the stated number of interviews.

Respondents failed to participant in all the waves of the study usually because we could not find them. Many withdrawals and comparison group members simply left the area, where graduates and continuing participants were more likely to still be living in the area. Others were not living in public housing but were in the area. Often, they would move several times between interviews without a forwarding address.

When we separate the responses by eventual program outcomes, we see that graduates were more willing to participate in multiple interviews; 58 percent had three interviews, and 29 percent had two interviews. Thus, we interviewed 87 percent of program graduates at least twice. Interviews with those who withdrew from the program and those who are continuing were somewhat less successful. Of those who withdrew, 39 percent had three interviews while 28 percent had two interviews. Among continuing participants, 32 percent were interviewed three times while another 34 percent were interviewed two times. Thus, we interviewed 67 percent of those who withdrew and 66 percent of those continuing, at least twice.