PHQ-9 Symptom-Configuration Heterogeneity Within Severity Bands (NHANES 2005–2018 Preregistered Analysis)

This is a preregistration of a descriptive analysis that examines the variety of PHQ-9 symptom profiles within the conventional severity bands using the combined data from the NHANES surveys from 2005 to 2018. Measures of profile richness and variety include the rarefied unique profile count and Shannon's effective number of profiles. This study does not include causal claims or hypothesis tests. To conduct the analysis, a fully reproducible workflow will be implemented that includes fixed decision rules, random seeds, and deviation recording.