State Child Welfare Policies and the Measurement of Child Maltreatment in the United States.

State-level child welfare policies and practices affect what can be referred, investigated, and substantiated as child maltreatment, and these institutional factors vary across states and over time. Researchers typically have not accounted for these factors in analyses, confounding institutional features with the underlying construct they seek to study. The present study addresses this limitation by demonstrating how changes in specific state child welfare policies and practices influence reported and substantiated maltreatment in the National Child Abuse and Neglect Data System (NCANDS). Using negative binomial models with state and year fixed-effects to analyze data from 2005 to 2018, we found significant influence of state policy and practice changes on state-level rates of reported and substantiated maltreatment over time. If a state implemented three of the most common policy changes-adding mandated reporters, centralized intake, and staff-its maltreatment reports were an estimated 32% higher than they would have been in the absence of these changes. By contrast, most state policy changes decreased the number of reports that were substantiated-by 24% if they implemented both differential response and higher standards of proof. Implications for future research and policy are discussed.