Hazard analyses permit the examination of the effects of multiple independent variables (in addition to experimental group membership) on rates of placement. They also provide somewhat more precise estimates of the effect of experimental group membership, since they control for the effects of the other variables in examining experimental-control group differences. In addition, they allow for the examination of "interactions" between other variables and experimental-control group membership, to see if the effects of experimental group membership differ for subgroups of the sample. We conducted Cox regression analyses of placement hazards using as predictor variables case characteristics available in the administrative data. Case characteristics in the administrative data are quite limited. Unlike the survival analyses which were conducted at the family level, hazard analyses were done at the child level because we wanted to include in them characteristics of children.
Kentucky. We examined the effects of the child's age, race, prior placement, and prior substantiated allegation of maltreatment, together with experimental group membership, on rates of placement. Regarding main effects, there were no significant predictors of placement. However, there was a significant interaction between experimental group membership and prior placement. Examining the differences in placement rates between the experimental and control groups by whether or not the child had had a prior placement indicates that among those with a prior placement, there is little difference in placement rates (32% for the family preservation group and 34% for the control group) while there is a significant difference for those without prior placement (22% for the experimental group and 14% for the control group). The interactions between experimental group membership and age and prior substantiated allegations were not significant.
New Jersey. New Jersey hazard analyses indicate that older age and prior placement increase the hazard rate significantly (p < .05; prior placement by 88% and each year of age by 3%). Experimental group membership was also significant (p < .08; experimental group membership increases the hazard rate by 97%). The interactions between experimental group membership and race, age, prior placement, and prior substantiated allegations were not significant.
Hazard analyses were also performed to examine the effect of county on placement. These analyses were conducted at the family level. Burlington county was chosen as the reference category, as it had the highest rate of placement. Thus, rates of placement in the other New Jersey counties are compared to the placement rates of Burlington. In addition to the county variables, experimental group and interactions of county with experimental group were entered into the regression equation. The hazard of placement for families was decreased by 67 percent for Ocean county, 73 percent for Monmouth county, 47 percent for Essex county, 57 percent for Bergen county, and 74 percent for Passaic county. The coefficient associated with Camden county was non-significant. There were no significant effects of experimental group or of county-experimental group interactions. This indicates that even after removing county variation, there are no significant differences between the experimental and control groups, nor does the effect of experimental group vary by county.
Tennessee. We examined the effects of the child's age, race, prior placement, prior allegation within 30 days of random assignment, prior substantiated allegation within 30 days of random assignment, and experimental group membership on rates of placement. Similar to Kentucky and New Jersey, we also explored interactions between experimental group membership and child characteristics. No significant interactions emerged. Only prior substantiated allegation had a significant effect on the likelihood of placement subsequent to random assignment. In the analysis of the CORS administrative data, a substantiated allegation within the last 30 days prior to random assignment increased the hazard rate by 209 percent. When unpaid relative placements were included ("any evidence") prior substantiation increased the hazard by 173 percent.