Administrative data from government departments and agencies provide detailed information on particular groups of migrants at the local level. These data sources have the advantage that they are usually ‘counts’ of the whole population of people coming into contact with a given government body or public service, and so they do not face the same problems of sample size that are common with survey data. The disadvantages of administrative data sources are that they:
- Only include people who interact with government agencies and so generally exclude some parts of the population.
- Can be affected by changes in how data are collected and processed over time.
- Often do not provide information on country of birth.
- Tend to provide limited information on the characteristics of migrants or their length of stay (since people do not have to ‘deregister’ when they leave the country).