Methodology
Disproportionality & Disparity Indices

Notes on Data Source

These reports compute ethnic Disproportionality and Disparity Indices based on population projections from the California Department of Finance. Please refer to the Population Data Index methodology for information on these data.
http://cssr.berkeley.edu/cwscmsreports/methodologies/default.aspx?report=Population

Disproportionality is the degree to which groups of children are present in the child welfare system at rates that are higher or lower than their presence in the general population. Although we compute a Disproportionality Metric (DM) for descriptive purposes, we do not recommend that it be used as a measure for comparing racial representation. The Disproportionality Metric is problematic due to its mathematical construction (which imposes a theoretical maximum based on the size of the minority group population). (For additional details, please see Shaw, T. V., Putnam-Hornstein, E., Magruder, J., & Needell, B. (2008). Measuring racial disparity in child welfare. Child Welfare, 87(2), 23-36.)

Instead, we recommend using a relative risk or relative rate ratio, which we refer to as a Disparity Index (DI). Disparity is used to refer to the lack of equity between groups and derived in one of two ways: either by computing a ratio based on the rates per 1,000 for two groups or by computing a ratio based on the disproportionality metrics for two groups.

These reports are based on the population of children who had child welfare system contact during a given year while between the ages of 0 and 17. Indices are stratified at the level of child welfare contact: Allegations, Substantiated Allegations, Entries, and In Care. Allegations are unduplicated counts of children for whom a child maltreatment allegation was received during the analysis year. Substantiated Allegations are unduplicated counts of children with a substantiated case during the analysis year. Entries to care are based on the count of unique children who entered care (both entries and re-entries) without restriction on the days spent in care. Entries and In Care Rates are restricted to cases supervised by a Child Welfare Agency.

Children with missing county assignment are included in the statewide calculation. Given the methods outlined above, county values may not sum to statewide total.

Disparity is computed for each ethnicity as it compares with every other ethnicity (i.e., Black vs. White, Black vs. Hispanic, etc.). In addition, disparity is computed for each ethnicity as it compares to “all others”, or the population of children who are not of the specified ethnicity. Please note that these Indices should be interpreted cautiously, especially at the county level. As is the case whenever a rate is computed based on a small population, large fluctuations and margins of error are common. For this reason, we have not included “Native American” as a comparison group in these reports. The population of Native American children in California is sufficiently small such that computed rates are quite inflated. If an examination of this population is desired, the Disparity Matrix Tool can be downloaded and used to compute rates for this and any other groups of interest.

Cells containing a period (".") represent a value of zero. In cells representing quotients, a period may also indicate the indeterminate form 0/0.

Disparity Indices are broken out by age and ethnicity. Please see the links below for additional details.

Age Group

Ethnic Group