In Kentucky and New Jersey, we examined a number of subgroups of cases to determine whether we could detect differences between experimental and control groups on placement and substantiated allegations subsequent to random assignment within each subgroup. The number of cases in Tennessee was not sufficient to support subgroup analysis. The results are shown in Table 8-2. Most of the subgroups were defined in terms of problems existing at the time of the initial interview. For both placement and substantiated allegations the table shows the number of cases in each subgroup, the percentage of cases in the subgroup experiencing the event within 6 months, the significance of the difference between the experimental and control groups in the occurrence of the event within six months, and the p value for the analysis of differences in survival curves. The first row of the table shows the results for the Kentucky and New Jersey samples as a whole. Except for substance abuse, the definitions of the subgroups were taken from the initial caretaker interview. Very few caretakers acknowledged substance use in the first interview, so that subgroup was determined from information in both the caretaker and caseworker initial interviews.
As can be seen, nearly all of the experimental-control group comparisons shown are not significant. Of the 36 comparisons in the table, only one is significant at .05, that for substantiated allegations in the single mother group in New Jersey.10 Among single mothers, those in the experimental group were less likely to have a substantiated allegation than those in the control group.
In the analysis so far, efforts to find subgroups for which family preservation service was related to reduced placement have been unsuccessful.
(10) The six months analyses and survival analyses are obviously not independent.