Change Score and Subscore Precision and Reliability of the Children's Depression Inventory.

Abstract

The Child Depression Inventory (CDI) is often used to assess change in depression over time, but no studies estimate the reliability of CDI change scores nor its five subscores. Our study investigated the reliability of change scores for both the total score on the CDI as well as its five subscores. We examined CDI responses from 186 maltreated children and estimated change score reliability for relative (e.g., comparison) and absolute (e.g., diagnosis) purposes. We also conducted subscore utility analysis, which determines if subscores have adequate reliability and provide information beyond the total score. We found that the total change score had acceptable reliability of .70 for our sample for both relative and absolute interpretations. In addition, the total score was a better predictor of true subscore values than the observed subscores-suggesting subscores did not add value over the total score, and that the reliability of changes in subscores was too low to be useful for any purpose. In summary, we found that the total CDI change scores were useful for assessing change in studies that examine relative or absolute change, and we advise caution when interpreting CDI subscores based on our analysis.