Can patient registers give an improved measure of internal migration in England and Wales?

This article describes a new source of internal migration data for England and Wales. These data are extracted from the 98 Family Health Service Authority (FHSA) patient registers that hold the details of people in England and Wales who are registered with the National Health Service. Migration estimates are derived from changes in postcodes on the patients' records. The findings presented in the article show that the registers provide high quality estimates of migration into and out of the constituent areas of the FHSAs (as compared to other sources). Where limitations are identified, compensatory adjustments can be introduced to further enhance the quality of the estimates.