Welsh Demographic Service (WDS)

Data Providing Organisation:
NHS Wales’ Informatics Service (NWIS)

Data Providing Type:
Administrative (mandatory) data return

Other – can be used for all themes


Administrative information about individuals in Wales that use NHS services; such as address and practice registration history. It replaced the NHS Wales Administrative Register (NHSAR) in 2009.

Data Collection Method

Data drawn from GP practices via Exeter System.

Data Highlights

This dataset provides linkage from anonymous individual to anonymous residences, thus enable to group households of individuals.

Access Requirements

As a core SAIL dataset available in accordance with our standard Information Governance procedure.

More Information

See the WDS website for more information.


All Wales population – approx. 3 million

Data Level

Individual person

Data Years

1990 – Present

SAIL Schema