Small Area Mental Health Index (SAMHI)

Summary 

The SAMHI is a composite annual measure of population mental health for each Lower Super Output Area (LSOA) in England. The SAMHI combines data on mental health from multiple sources (NHS-Mental health related hospital attendances, GP Patient Survey – Q34 Best describe your own health state today, Prescribing data – Antidepressants, QOF - depression, and DWP - Incapacity benefit and Employment support allowance for mental illness) into a single index.

Technical description 

Each indicator was individually standardised by ranking LSOAs from best to worst and its direction of association to mental health and then transformed to the standard normal distribution by using the Rankit method which is a rank-based inverse normal transformation. Maximum likelihood factor analysis is used as a method for combining indicators (by finding appropriate weights) into a single score based on the inter-correlations between all the indicators.