Statistical estimation of child abuse rates from administrative databases

Increasingly, child welfare agencies need to provide statistical summary reports on the safety of the children for whom they are responsible. Often these summaries include ordinary period rates of child abuse derived from administrative data. These indices fail to adjust for the length of exposure to risk, such as time in foster care during the year. Since duration of care often differs by living arrangement, race, gender, and other variables, the use of such period rates to measure child safety or abuse may bias comparisons over time or across groups. This bias may lead to misperceptions of trends in safety over time, and of the comparative safety of different modes of care. This article discusses fundamental issues in the extraction, from administrative data, of valid measures of child welfare outcomes targeted to specific populations. In addition, it provides an introduction to exposure adjustment of child welfare measures based on information that is generally readily available in administrative databases. Cohort-based incidence density rates are recommended in preference to period prevalence from cross-sectional data. Survival modeling/multiple event history analysis is described for more complex situations. The ready availability of such analytic tools suggests further directions for quantitative research in child welfare monitoring.