The International Passenger Survey (IPS) is a sample survey of people arriving at and departing from UK main airports and sea routes and the Channel Tunnel
The IPS surveys approximately 700,000 to 800,000 passengers per year, 4,000-5,000 of which are identified as long-term international migrants. The survey, conducted by the ONS (Office of National Statistics), covers these three main areas: expenditure, tourism and migration. Although the IPS was not designed primarily to derive information on international migrants, the survey asks respondents about their migration intentions and yields information consistent with the UN definition of international migration: to stay or leave the UK for more than 12 months. Data collection on people leaving the UK is one of the key advantages of the IPS – it is the only data source measuring emigration. Another strength of the IPS is the relatively rich information on the type of migration and characteristics of the migrants. Interviewees are asked about the main reason given for movement in or out of the country (definite job, looking for work, accompany / join, study, working holiday, other). Data can be broken down by nationality, sex and age group. The IPS, with a few added adjustments by the ONS, is the basis of LTIM (Long-Term International Migration) data, the official government statistics on immigration, emigration, and net migration.
The coverage of the IPS is not comprehensive. The IPS excludes migration over the land border between the UK (Northern Ireland) and Ireland due to the existence of the Common Travel Area (CTA) between the two countries. It also excludes most asylum seekers and their dependants.
Migration estimates are based on respondents’ initial intentions, which may not accord with what they do in practice, e.g. in terms of duration of stay.
As the number of migrants in the sample is relatively small, estimates for subsets of the sample are subject to substantial uncertainty. For example, sampling errors are too large to measure with a reasonable degree of accuracy the number of migrants to a single region of the UK, or from a single country of origin (aside from the 4-5 largest national groups) or from a single age group.