Travel trends: 2015

1. The figures relate to the number of completed visits, not the number of visitors. Anyone entering or leaving more than once in the same period is counted on each visit. The count of visits relates to UK residents returning to this country and to overseas residents leaving it.

2. Day-visits (that is trips that do not involve an overnight stay) abroad by UK residents as well as day trips to the UK by overseas residents are included in the figures for visits and expenditure. Note 3 in sub-section Traveller Exclusions refers to overseas residents in transit through the UK. Please note day visits to or from the Republic of Ireland across the land border are excluded, although they are included in total visits.

3. An overseas visitor means a person who, being permanently resident in a country outside the United Kingdom, visits the UK for a period of less than 12 months. UK citizens resident overseas for 12 months or more coming home on leave are included in this category. Visits abroad are visits for a period of less than 12 months by people permanently resident in the UK (who may be of foreign nationality).

4. When a resident of the UK has visited more than one country, the entire visit, expenditure and stay are allocated to the country stayed in for the longest time.

5. Visits for miscellaneous purposes include those for study; to attend sporting events; for shopping; health; religious; or for other purposes; together with visits for more than one purpose when none predominates (for example, visits both on business and on holiday). Overseas visitors staying overnight in the UK en route to other destinations are also included in miscellaneous purposes.

6. Estimates relating to tourist flows across the land border between the Republic of Ireland and Northern Ireland are, for convenience, included in the figures for sea. Where not shown separately, flows through the Channel Tunnel are also included under the figures for sea.

7. Estimates relating to tourist flows across the land border between the Irish Republic and Northern Ireland are excluded from the regional analysis tables (except the ‘Total’ section) as are all visits that did not include an overnight stay in the UK. Visits by overseas residents to Northern Ireland, although included in the ‘total’ column, are not separately analysed. More than one region can be visited by an individual while in the UK so the total of the visits to all the regions will be greater than the total number of visits to the UK as a whole.

8. Adjustments are made to the reported cost of an inclusive tour so that only the amount earned by the country of visit (for example accommodation costs, car hire, etc.) is included. This estimate is then added to an individual's spending to give the total spending in the country of visit (see also note 10).

9. Length of stay for UK residents cover the time spent, including the journey outside the UK, whilst for overseas residents it refers to the time spent within the UK.

10. Earnings and expenditure figures cover the same categories of travellers as do the number of visits, except that in addition the earnings figures include the expenditure by same day transit passengers, and the foreign exchange earnings and expenditure due to travel relating to the Channel Islands and other (non-UK) countries. They exclude payments for air, sea and rail travel to and from the UK.

11. Spending reported in this report and other ONS Overseas Travel and Tourism publications covers money spent in association with overseas travel and tourism, but excludes fares for travel to or from the UK. For any traveller on an inclusive tour, an estimate of the return fare is deducted from the total tour price. Inclusions and exclusions are driven by Balance of Payments definitions, and main specifics are listed in points 12 to 16 as follows:

12. Only money sourced outside the country of visit is included. Thus, any money earned and subsequently spent by an overseas resident on a visit to the UK is excluded.

13. In addition to money spent during the visit, certain expenditure before or after the visit is included in spend estimates. Such expenditure includes items such as deposits, car hire, theatre tickets, short course fees, tickets for internal travel in the country of visit, travel insurance if bought prior to this particular visit.

14. Purchase for personal export of large items such as cars or boats are excluded from expenditure. However, if the car was bought abroad and not brought back to the UK, the spending would be included. Cost of any house purchase abroad is excluded. Any money spent abroad for the purpose of improving or renovating a property is included however, as is any expenditure abroad on legal fees to do with a house purchase.

15. Expenditure by UK residents on board UK-owned cruise ships is excluded, but expenditure on visits ashore during a cruise is included. Any money spent abroad (for example, on medical treatment) which will be refunded through an insurance company inside the country of visit will be excluded. Private school fees are excluded.

16. An estimate for purchases by overseas visitors at airport duty-free shops is included in the figures for spending. Such purchases on British carriers are excluded.

Traveller exclusions

The following groups are excluded from the tables in this publication:

1. Trippers who cross the Channel, North Sea or Irish Sea but do not alight from the boat (called stay-on-board).

2. Migrants and persons travelling to take up prearranged employment, together with military or diplomatic personnel, merchant seamen and airline personnel on duty.

3. Overseas residents passing through the UK en route to other destinations, but who do not stay overnight (often known as transit passengers). However, any spending by transit passengers while in the UK is included in the spending figures.

Geographical areas

1. North America: Canada (including Greenland and St Pierre at Miquelon), USA (including Puerto Rico and US Virgin Islands).

2. Europe: All countries listed within the European Union (see below for listing) plus the following central and eastern European countries; North Cyprus; Gibraltar; Iceland (including Faroe Islands); Norway; Switzerland (including Liechtenstein); Turkey; the former USSR; and the states of former Yugoslavia.

3. EU15: All countries that joined the European Union before 1 January 2004; Austria; Belgium; Denmark; France (including Monaco); Finland; Germany; Greece; Republic of Ireland; Italy (including San Marino and Vatican City); Luxembourg; Netherlands; Portugal (including Azores and Madeira); Spain (including Canary Islands; the Balearic Islands and Andorra); and Sweden. Note that the UK is among the 15 countries that formed the European Union prior to January 2004, but due to the nature of the data displayed in the IPS datasets data for the UK is excluded.

4. European Union: All countries that are current members of the European Union; Austria, Belgium, Bulgaria, Croatia*, Cyprus**, Czech Republic, Denmark, Estonia, France (including Monaco), Finland, Germany, Greece, Hungary, Irish Republic, Italy (including San Marino and Vatican City), Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal (including Azores and Madeira), Romania, Spain (including Canary Islands, the Balearic Islands and Andorra), Slovakia, Slovenia and Sweden. Note that the UK is a member of the European Union but due to the nature of the data displayed in the IPS datasets data for the UK is excluded.

5. Other European Union: All countries that joined the European Union from 1 January 2004 onwards; Bulgaria, Croatia*, Cyprus**, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Romania, Slovakia and Slovenia.

6. North Africa: Algeria, Libya, Morocco and Sudan.

7. Other Middle East: Bahrain; Iran; Iraq; Jordan; Kuwait; Lebanon; Oman; Qatar; Saudi Arabia; Syria; and the Yemen.

8. Central and South America: Argentina; Belize; Bolivia; British Antarctica; Brazil; Chile; Colombia; Costa Rica; Ecuador; El Salvador; the Falkland Islands; French Guiana; Guatemala; Guyana; Honduras; Nicaragua; Panama (including Canal Zone); Paraguay; Peru; Surinam; Uruguay; and Venezuela.

9. Other Caribbean: Antigua; Bahamas; Bermuda; British Virgin Islands; Cayman Islands; Cuba; Dominica; the Dominican Republic; Grenada; Haiti; Martinique; Montserrat; St Kitts-Nevis-Anguilla; St. Lucia; St. Vincent and the Grenadines; Trinidad and Tobago; Turks and the Caicos Islands.

• Croatia joined the European Union on 1 July 2013 and data relating to Croatia collected from that date onwards has been included in the 'European Union', 'Other EU' and 'Europe' categories. Data relating to Croatia collected prior to 1 July 2013 is included in the 'Europe' category only.

** Only the south of Cyprus is a member of the EU but the IPS is unable to separate North and South Cyprus for the period before May 2004 and so all of Cyprus is included in the European Union section until May 2004. From May 2004, only southern Cyprus is included in the European Union figures.

Although the information in this publication is by the country groups described above, almost 200 different countries of residence or visit can be identified on the main IPS datasets.

Main concepts and variables

Flow

Respondents in the International Passenger Survey (IPS) are mainly identified and analysed by their ‘flow’. Flow is described as the direction of travel of the visitor combined with whether they are a UK resident or an overseas resident. There are, therefore, 4 main flows on the IPS:

• overseas residents departing from the UK
• UK residents departing from the UK
• overseas residents arriving in the UK
• UK residents arriving in the UK

Only data on overseas residents departing from the UK and UK residents arriving in the UK have been used in this publication. This is because the IPS interviews for these travellers take place at the end of their visits when factual information about visit duration and spending is available. This is felt to be more complete and reliable than the information gathered at the beginning of a trip when intentions regarding duration and spending may not prove to be accurate.

Number of visits

The data in this report relate to the number of visits not the number of visitors. Those entering or leaving the UK more than once in the same period are counted on each visit.

Purpose of visit

The IPS records the many different reasons people have for making a visit. These are combined into four main analysis categories:

• holiday (Holiday/pleasure, to play amateur sport, cruise)
• business
• visiting friends or relatives
• miscellaneous

The categories describe the main purpose of the visit and, where it is not possible to determine this, the respondents’ reason for the visit is categorised as ‘miscellaneous’. People migrating (to or from the UK) or travelling as crew of aircraft, ships or trains are excluded from analyses in this publication.

The IPS collects information on whether tourists travel independently or on some form of package trip. As well as providing data on all holiday visits, this report also provides information on those who are on package holidays, which are referred to as ‘inclusive tours’. Such visits are defined as holiday visits on which accommodation was paid for as part of an inclusive tour or where fares and accommodation cannot be separated.

The business category includes conference and trade fair visits. Those who made their visits for study, medical treatment or shopping appear in the miscellaneous category. More detailed information on the main reason for visits (such as attending conferences or trade fairs) is available from the IPS datasets (see Appendix F).

Some analyses show data for ‘leisure’ and ‘business’ visits, where the ‘leisure’ category includes all visits for holidays, visits to friends or relatives, and visits for miscellaneous purposes.

People migrating (to or from the UK) or travelling as crew of aircraft, ships or trains are excluded from analysis in this publication. Country of residence or visit.

For overseas residents visiting the UK, this is the main country of residence of the visitor. For UK residents travelling abroad, it is the main country of visit.

Although the IPS collects information on all individual countries of the world, many countries outside of Europe are shown within groups rather than individually. It would not be practical to show all countries separately but also for many countries, sample sizes are too small to give accurate estimates.

Appendix B shows how the countries of the world are grouped into the areas used in this report.

UK region of stay

The IPS records which towns overseas residents stayed at least one night in when they visited the UK. However, due to the very large number of towns in the UK it would not be meaningful to produce analyses of visits by the full range of towns. In this publication, visits information for overseas residents is therefore mainly shown at county or unitary authority level, and main UK region levels, although a table of the top 50 towns visited is also included.

In 2007, a more accurate approach to coding towns was employed in the survey, based on a more comprehensive coding frame of towns and boroughs. This may result in a slight discontinuity from previous years and care should therefore be exercised when comparing results with earlier years.

Care must be taken when using the regional information, as the numbers of visits to separate UK areas cannot simply be added together to form larger regions. This is because a person may stay in more than one area of the UK during a single visit. As a result, the numbers of visits to smaller areas do not sum to the figures given for larger regions in the regional tables in this publication.

For example, a person staying at least one night in each of London, Windsor and Aberdeen in a single visit to the UK would appear as one visit to London, one to Berkshire and one to Grampian. However, the same visitor would be recorded as a single visit in the England total and a visit in the Scotland total, and as just one visit in the UK total. Although visits cannot be summed across UK regions, the amount of spending and the number of nights stayed can. (See Appendix A, point 7 for an explanation regarding visits to Northern Ireland.)

UK region of residence

For UK residents, data are presented by the region of residence, that is London, the rest of England, Scotland and Wales.

Mode of transport

Until 1994 air and sea were the only two main modes of transport to and from the UK. The Channel Tunnel between the UK and France began operating towards the end of 1994. Information on passengers using the tunnel is available on the IPS from the fourth quarter of 1994. Journeys by sea and tunnel are further analysed to show whether a vehicle was taken on the trip and, if so, the type of vehicle that was used.

Age and sex

Respondents’ age and sex are collected in the IPS interview. Questions on exact age are not asked on the IPS and instead respondents are classified into age groups as it is felt that some people may not give accurate answers, and age groups are normally sufficient for users’ needs.

All travellers, including children under 16, are eligible to be interviewed on the IPS. If the sampled person is under 16, where possible the interview is carried out with the child after having first received permission from a parent, guardian or responsible adult travelling with them (for example, a school teacher if they are on a school trip). If the child is too young to complete the interview themselves, proxy information is collected from the parent, guardian or responsible adult, wherever possible.

Expenditure

Expenditure for both UK and overseas residents exclude amounts spent on fares to and from the UK.

Visits and expenditure information regarding travel to or from the Republic of Ireland for years up to and including 1998 are included in the figures for the EU but do not appear separately in the rows and columns of some tables. Consequently, rows and columns in the tables may not always sum to the figures shown for the whole EU.

Expenditure data relating to the Channel Islands are included within the figures for Europe but are not shown separately. This means that spending shown for the individual countries of Europe will not always sum to the figures shown for the whole of Europe.

Expenditure data of overseas visitors transiting the UK, but not staying overnight, are included within the figure shown for ‘All purpose’ of travel, but are not shown separately. This means that spending shown for overseas residents’ visits by individual purpose of visit will not always sum to the figure shown for ‘All purposes’.

Travellers to and from the Republic of Ireland

There is a major discontinuity in the time series shown in this publication between years up to and including 1998 and subsequent years. From the second quarter of 1999, the IPS began interviewing on air and sea routes between the UK and the Republic of Ireland. For the years up to and including 1998, estimates of visitor numbers, their spending and nights stayed on routes between the UK and the Republic of Ireland and their characteristics were based on data provided by the Central Statistics Office of the Republic of Ireland. From 1999, and for subsequent years, this report uses IPS interview data. To enable 1999 data to be analysed, data for the first quarter of 1999 were constructed, based upon interviews conducted in the first quarter of 2000, but weighted to the traffic volumes of the first quarter of 1999.

Analysis of the interview data from 1999 onwards has shown that a large number of Irish visitors who would previously have been defined as tourists to the UK were transiting through the UK on their overseas visits. Also, the data for 1999 onwards showed that a number of European and Commonwealth visitors made combined visits to the UK and the Republic of Ireland; these visits were previously recorded as visits from residents of the Republic of Ireland.

These factors combined to reduce the number of overseas visitors to the UK from 1999 onwards, mainly the estimates of visitors from the Republic of Ireland, but they also increased the number of visitors from certain other countries, particularly Australia, New Zealand, Canada, Germany and the Netherlands.

The data from the IPS Irish interviews also affected estimates of spending and nights. These showed that the previous estimates of spending per visit of Irish visitors to the UK were overstated, while estimates of UK residents’ spending per visit in the Republic of Ireland were previously understated.

The interview-based details of visitors from the Republic of Ireland have enabled more completed duration of stay and regional breakdowns to be produced from 1999 onwards. This has led to discontinuities between 1998 and 1999 in the duration of stay and regional profile from the IPS.

In summary, the major effect resulting from IPS interviewing on routes to and from the Republic of Ireland was to improve the quality and detail of estimates from 1999 onwards. The discontinuities from this change affected time series estimates of visitors to and from the Republic of Ireland, with some smaller effects for other countries.

Background

The International Passenger Survey (IPS) is a large multi-purpose survey that collects information from passengers as they enter or leave the UK. It is carried out by the Office for National Statistics (ONS) for a range of public and private sector organisations. In particular, the survey provides figures used for the travel account of the balance of payments, international migration statistics, and for informing decisions on tourism policy.

The data from the survey are widely used across and outside of government to provide detailed information on the numbers and types of people travelling to and from the UK. Results are published regularly by ONS on a monthly, quarterly and annual basis. More detailed analyses are possible through the Data, Advice and Relations Team (DART) in ONS, or by downloading the travelpac dataset from our website.

Travellers passing through passport control are randomly selected for interview and all interviews are conducted on a voluntary and anonymous basis. Interviewing is carried out throughout the year. The overall response rate (complete and partial interviews) for the 2015 survey was 78.4%.

Since the IPS began in 1961, its coverage has been extended so that it includes all the main air, sea and tunnel ports or routes into and out of the UK. The only routes excluded from the survey are sea routes to and from the Channel Islands, the land border with the Republic of Ireland, and cruise ships travelling to and from the UK.

Approximately 95% of passengers entering and leaving the UK are covered by the survey. The remainder are either passengers travelling at night, when interviewing is suspended, or on those routes too small in volume or too expensive to be covered.

The IPS data are weighted to produce national estimates of all international travellers to and from the UK on a quarterly basis. Although some provisional monthly data from the IPS are also published, a single quarter is the minimum period over which most detailed analyses of the data can be made. Annual national estimates are created by combining the 4 quarters of the year.

The calculation of the weights on the IPS takes into account its complex sample design and information provided from other sources on, among other things, the non-sampled routes and time periods. For example, the Central Statistics Office in the Republic of Ireland provides information on travellers crossing the land border with Northern Ireland.

Overview of the survey design for collecting Overseas Travel and Tourism information

The IPS is based on face-to-face interviews with a sample of passengers travelling via the principal airports, sea routes and the Channel Tunnel. The number of interviews conducted to produce overseas travel and tourism estimates in 2015 was 335,500, this large sample size allows reliable estimates to be produced for various groups of passengers despite the low proportion of travellers interviewed.

The IPS sample is stratified to ensure it is representative by mode of travel (air, sea or tunnel), port or route, and time of day. The frequency of sampling within each stratum is varied according to the variability of tourist expenditure and the cost of interviewing.

For example, where the expenditure quoted on a particular route varies greatly across respondents, a higher sampling frequency is used to enable a more satisfactory estimate to be produced. (For further details on the sample design, see the Sampling section and the IPS Overseas Travel and Tourism User Guide (Volume 1): Background and Methodology).

Some questions on the survey are asked of all of the passengers interviewed, while others are restricted to certain specific sub-groups. Information on the spending and length of stay of UK residents abroad and overseas residents in the UK is only collected on the return leg of a visit. This is because actual spending and length of stay are required, and these may differ from the respondents’ intentions when they start their visit. In 2015, the sample on which the estimates presented in this publication are based included 41,800 interviews carried out with overseas residents departing from the UK and 60,600 with UK residents arriving back from abroad.

The details collected on the survey are used by ONS, along with other sources of information, to produce overall national estimates of the number and expenditure of different types of travellers. A complex weighting procedure is used to do this that takes into account various factors in order to improve the estimates. (For further details of the weighting procedure, see the Producing national estimates section).

The collection of the IPS data

The key to producing reliable results from the IPS lies initially in the way the data are collected. Great emphasis is therefore placed upon the IPS interviewers to ensure they are able to capture data efficiently and accurately.

Nationally, IPS data are collected by a team of over 200 interviewers who are recruited and trained specifically to work on the IPS. Interviews are carried out on all days of the year, apart from Christmas Eve, Christmas Day and Boxing Day.

Almost all IPS interviews take place on a face-to-face basis with the responses being initially recorded on paper forms. In recent years ‘self completion’ questionnaires have been used at times where an interviewer has been unable to conduct an interview because of language difficulties.

Due to the layout and facilities at some seaports it is not always possible to interview passengers as they arrive. In such cases, IPS staff travel to seaports in France and Ireland to select their subject and then conduct interviews which take place either at the overseas ports of departure, or on board the vessels returning to the UK.

Shortly after the interview has taken place, the data are transferred to a computer system in which electronic checks are made of the data being input and the data is then transmitted to ONS headquarters where a series of further quality and accuracy checks are made on the data before processing and analysis.

More information about the collection of IPS data can be found in the IPS Overseas Travel and Tourism User Guide (Volume 1): Background and Methodology.

Sampling

The IPS uses a multi-stage sample design. The sampling for air, sea and tunnel travel is carried out separately, although the underlying principle for each mode of travel is broadly similar. In the absence of a sampling frame of travellers, time periods/shifts or sea crossings are selected at the first stage (primary sampling unit), and travellers are then systematically chosen at fixed intervals from a random start within these shifts or crossings at the second stage. The details of the sampling scheme for each individual mode of travel are described below. More information about the IPS sample design can be found in the IPS Overseas Travel and Tourism User Guide (Volume 1): Background and Methodology.

Within the overseas travel and tourism sample, a higher percentage of people starting their visit than ending it has been noted. This is important because the overseas travel and tourism estimates are based on the number of completed visits (that is, are drawn from interviews with UK residents as they arrive in the UK and with overseas residents as they depart the UK). A weighting stage, known as the “imbalance weight”, has been included in the weighting of travel and tourism data to reduce the difference in profile between the arrivals and departures samples. A paper outlining the imbalance present in the IPS travel and tourism sample can be found on our website. This imbalance weight is currently under review and findings will be published.

Air routes

For air routes, time periods are sampled. Shifts are selected for the first stage. These are done in such a way that the numbers of shifts are balanced between mornings and afternoons, and days of the week within any quarter. At the second stage, passengers are counted as they cross a predetermined line and every nth person is interviewed.

The sampling interval, n, differs between sites and involves a first stage sampling rate used to screen respondents for migration purposes and a second stage sampling rate used for overseas travel and tourism interviews. Departing passengers are sampled at a higher rate than those arriving because the expenditure information for overseas residents visiting the UK is more variable than that for UK residents returning from visits abroad.

A small number of shifts every quarter are also conducted at other smaller international airports in the UK. However, the sample size is insufficient to provide accurate estimates for most of these airports individually. Those airports with less than about 250,000 passenger movements per quarter are usually excluded from the survey altogether on the grounds of cost effectiveness, but traffic at these sites is taken into account when producing national estimates.

Sea routes

Sea routes carrying 50,000 passengers a year or more are generally included in the IPS sample. At some seaports, passengers are sampled and interviewed on the quayside as they embark or disembark, while at others IPS interviewers travel on the boat itself with interviewing being carried out on board. The choice between interviewing on the quayside or on crossings is made on practical grounds such as cost, safety and permission.

Where interviewing is conducted on the quayside, the sample is designed to select shifts that are balanced across different days of the week and times of day within a quarter, with each individual shift covering several sailings. Where interviews are conducted on crossings, a predetermined number of return crossings are selected for each route, spread across time of day and day of week each quarter. As for air sampling, sea passengers are selected at fixed sampling intervals from a random start within each shift or crossing. The IPS also sample also includes long haul ships capable of carrying more than 200 passengers arriving and leaving from Southampton.

Tunnel routes

The method used for the tunnel routes is different for Eurostar passenger trains and for Eurotunnel vehicle shuttles.

The method for passenger trains is similar to that for air travel; time shifts are selected and then passengers are selected at fixed intervals within the time shift. Passengers are interviewed after crossing a predetermined line at Ebbsfleet, St. Pancras, and Ashford International stations on arrival or departure.

In contrast, for vehicle shuttles, crossings are randomly selected and interviewing takes place on board the shuttles themselves. Because of time constraints, only a certain number of interviews can be carried out on any individual shuttle and the sampling interval used is therefore dependent on traffic volumes.

Producing national estimates

Once the information has been collected from respondents, the survey data are weighted to produce national estimates, which are then published on a monthly and quarterly basis as provisional estimates and final estimates published annually.

The basis of the weighting of IPS survey data is that the total set of respondents interviewed at a port or route is weighted up/calibrated to passenger traffic known to have passed through that port or route in the period in question. The known passenger traffic information is provided to the IPS team by the Civil Aviation Authority, Department for Transport, Eurostar, Eurotunnel, Heathrow Airport Holdings and a number of airports themselves.

The weighting approach incorporates a number of stages which take account of all passengers selected for interview. Weighting is conducted for each port/route and direction of travel combination, employing the same principles at each one. The stages, listed in order of application, are as follows.

Stage 1

A Design weight is employed, to account for the probability of sampling this passenger using the first-stage sampling rate.

The calculation compares the number of shifts or crossings sampled (at each port/route and direction of travel combination) with the number of shifts or crossings that could have been sampled for that combination in the period. In addition it takes into account the first-stage sampling rate. For example, in a case where a contact was sampled at a port with the following details:

• 10 shifts were run in the period
• 100 shifts could have been run in the period
• the contact was the sample employing a first stage sampling rate of 20 (that is, every 20th passenger was selected)

The design weight for this contact would be 200, calculated as (100/10) x 20. As well as port/route and direction, this weight incorporates weekday or weekend, and am, pm or night as weighting strata.

Stage 2

A Non-response weight factor is employed to take account of contacts selected for interview but who were subsequently not interviewed, either because it was not possible to contact them or they refused to participate.

The weight is applied at each port/route and direction of travel combination and also incorporates weekday versus weekend as weighting strata. It involves uplifting ‘complete’ and ‘minimums’ cases by a factor calculated as:

• the sum of weights applied to all ‘completes’, ‘minimums’ and ‘non-response’ records
• divided by the sum of ‘completes’ and ‘minimums’ at that port/route and direction of travel combination

Stage 3

A second design weight is applied to account for the second-phase of the sample design and relates to the sub-sampling of non-migrants. The weight for this factor is simply equal to:

• the ratio second-stage sample interval: first-stage sample interval for non-migrants, and
• 1 for migrants.

Stage 4

A weight factor is applied for discarding minimum respondents. Minimum interviews are discarded in this step of the weighting, with other cases weighted up to compensate. The purpose of applying this weight is that it is possible that the profile of minimums might be skewed to certain nationalities or residents of certain countries (for example, driven by language difficulties meaning that only minimal information is provided to the interviewer).

This weighting step works to the same principle as the non-response weight. It utilises port/route and direction of travel as weighting strata.

Stage 5

Weighting to the sampling frame. Here the population (that is, passenger traffic) or the ports and routes covered by the sampling frame are used to weight the data. The population excludes interlining passengers (those neither entering nor leaving the UK from this port, that is, simply changing international flights) and out-of-hours traffic (that is, arriving or departing outside the hours covered by the IPS interviewing at that port). The weight is applied at each port/route and direction of travel combination.

Stage 6

Weighting for frame under coverage. This extends the above population weighting to compensate for not covering certain ports and times of day (out-of-hours traffic) in the survey sample. The weight utilises port/route and direction of travel as weighting strata and also incorporates region of the world that traffic has come from/gone to. The weight reflects the fact that flights to and from some parts of the world are more likely than others to arrive, or take off at night, when no interviewing is conducted at airports.

Stage 7

Weighting for observed imbalance. This step is used to correct an observed imbalance between the number of non-migrants entering and leaving the UK. These are applied as a series of fixed factors, relating to direction of travel, port/route and country/residence. It has been noted that during 2009 and 2010 there was an increase in the proportion of respondents in the IPS overseas travel and tourism sample who are starting their visit compared with the proportion ending their visit. This proportion of the two types of traveller in the sample defines the estimates of travel and tourism.

There is no clear reason for this trend, ONS has taken steps to calibrate its overseas travel and tourism estimates with external data, notably estimates from surveying conducted at departure gates at main airports in the UK by the Civil Aviation Authority (CAA) and e-borders data. This work showed general consistency between the datasets with the result that the factors used in the imbalance weight have been retained. More information about the work undertaken to explore the imbalance and planned future work can be found on our website.

Stage 8

A final weight is applied, which combines each of the weighting stages listed above.

Imputation

Where the responses for key items of interest are missing from the survey data for an individual record the values are imputed. Imputation is applied to the following items:

• Length of stay
• Cost of fare (expressed in terms of cost of the single fare for the respondent) • Spend • Town of stay

For each of length of stay, cost of fare and spend, a value is calculated for the survey record which had the information missing. The IPS employs a mean-value within class imputation procedure where the missing value is replaced with the average value for records with similar characteristics. The matching variables used for each of these items are:

• Length of stay: Country of visit/visiting from; Purpose of visit
• Cost of fare: Port in UK travelling to/from; Overseas port travelled to/from; Month of travel; Operator
• Spend: Country of visit/visiting from; Duration; Purpose of visit

Where the respondent has travelled on a package holiday, the cost of the fare is imputed and then deducted from the total cost of the package, and the residual cost (after removal of a percentage to cover travel agent fees) is assigned to expenditure. Overseas residents staying in the UK are asked about their total expenditure in the UK. This information is then imputed across the towns stayed in, proportionate to the length of stay in each one. It is recognised that people tend to spend more when they stay in London than in other towns in the UK and therefore an uplift index is calculated and applied to the spend allocated to London in cases where the respondent stayed in both London and other towns in the UK.

In cases where an overseas resident hasn’t given details of all the towns in the UK they stayed in, an uplift is applied to towns stayed in by similar records, using the same principles as outlined above for the imputation of stay, fares and spend.

Seasonal adjustment

The number of travellers and their spending both have a clear seasonal pattern, with more visits and spending in the summer than in the winter. Statistical techniques are used by ONS with the package X-12-ARIMA to produce seasonally adjusted figures. These figures show visits and spending with an estimate for the seasonal component removed. They allow more meaningful comparisons to be made between months and quarters of the year and help to identify underlying trends.

More details on seasonal adjustment procedures can be obtained from our IPS Branch.

Constant prices

Usually, spending by overseas residents in the UK and UK residents abroad grows each year as the price of goods and services rise. Constant price figures are calculated by ONS to show real spending across years with the effects of price inflation removed.

For overseas residents’ expenditure in the UK, an index is created by splitting spending into its component parts (accommodation, meals and so on) using past IPS data and uprating these components by their related retail price indices. The resulting index is then used to rebase the overseas figures back to 1995 prices.

For UK residents abroad, spending is split by country of visit. Consumer price indices for particular countries are used with currency conversion rates to produce an index of price rises. The index is then used to rebase UK residents’ spending to 1995 prices.

Additional sources of data

The method above explains how the national estimates are produced based on the routes sampled on the IPS. Unfortunately, as the IPS does not cover all passenger routes, additional figures have to be obtained from other sources or estimates and added to the totals derived from the IPS. These additions are:

• UK residents on cruises departing from or arriving at UK shores
• Channel Islands expenditure and receipts from tourism
• rail fares purchased by overseas visitors to the UK and UK visitors abroad before the start of their visit
• estimates of travel across the land border between Northern Ireland and the Irish Republic, from the Irish Central Statistics Office.

Changes in methodology introduced in 2005

Due to a rapid growth in traffic, 2 new residual airports, Liverpool and Prestwick were introduced into the IPS sample in 2005 for the first time. The introduction of these 2 airports has some implications for the results of the IPS. The inclusion of these 2 ports means that there is more likelihood of picking up contacts that reside in, or have visited areas close to, these airports.

The introduction of the new airports caused the IPS research team to review the way that traffic from airports not sampled by the IPS is accounted for in the IPS processing systems. As a result, the systems were modified slightly in order to prevent overestimates or underestimates of traffic occurring at a regional level.

The introduction of the new airports and the subsequent changes made to the processing systems causes a discontinuity in the IPS results. Any comparisons of IPS results for 2005 onwards with earlier years (and especially those of a UK regional nature) therefore should be made with care.

Changes in methodology, 2007

Imputing expenditure

The methods of computing expenditure (imputation) for cases where no expenditure information is given by the contact changed in 2007. The new method takes account of the duration of stay of the contact which had not been the case previously and means there may be a discontinuity in the expenditure series from 2006 to 2007. The new methodology compensates for possible overestimates of spending which may have arisen in the past due to the average daily spending being generally lower on longer trips than on shorter ones.

Imputing fares

The costs of a package trip normally include fares to and from the country of visit. For expenditure estimates the fares are deducted from the cost of a package in order to obtain the amount of spending on the visit. The manual method of looking up fares from brochures and from the internet was replaced in 2007 by an automated system which uses fares data provided by the respondent.

Coding of UK towns

In 2007 a more comprehensive approach to coding UK towns was introduced. Interviewers were provided with a more detailed list of towns and boroughs than in the past, meaning that their recording of responses given by respondents was more accurate.

Changes in methodology, 2009

Aberdeen Airport was introduced to the sample, and as a result, the estimated number of visits to cities and regions in Scotland will have been impacted positively. Belfast International Airport was also introduced but visits to cities and regions in Northern Ireland are not reported in the IPS Overseas Travel and Tourism estimates due to inability to record details of visits made by crossing the Irish land border.

Prior to 2009, known passenger traffic passing through Belfast was allocated to airports in Great Britain. The allocation of this traffic to interviews conducted in Belfast in 2009 will have had some downward impact on estimates of visits to towns and regions in Great Britain. (Airports at Doncaster, Southampton and Bournemouth were added in 2008).

More broadly, the overall methodology of the IPS was changed in 2009, in terms of both sampling and data processing.

Sampling was revised to incorporate an increase in the number of shifts run at many ports outside of Heathrow and a decrease in the number of shifts run at Heathrow. This change was introduced following a Port Survey Review in response to the recommendations put forward by the Inter-Departmental Task Force on Migration Statistics.

Further, the way that shifts are run was changed via the introduction of a system employing a primary sampling interval for screening migrants and a sub-sample interval for travel and tourism contacts. This approach didn’t affect the profile of travel and tourism contacts but it did require a change in the way the data is processed.

The data processing involves weighting of all records and imputation of records with information missing at certain questions. The basic principles behind the processing were retained in 2009 but improvements were made in some aspects. This resulted in some discontinuity with a downward impact of approx 2% in visits to the UK and 3% in visits overseas and a further value of less than 1% in earnings and expenditure.

There have been no changes in data collection methodology since 2009. However, the methodology used to estimate the number of UK residents departing from or arriving at UK ports on cruises was revised in 2010. The new methodology utilises new sources of data, including that published by DfT, IRN Research and the European Cruise Council. This represents an improvement in methodology and has the effect of increasing the estimated number of visits to ‘rest of the world’ by UK residents by approximately 175,000 compared with 2009.

Changes in methodology, 2014

In June 2014, Heathrow Terminal 2 was opened and flights were gradually moved from T1, T3 and T4 into the newly opened Terminal 2. Terminal 2 was included in the sample in August 2014. The Newhaven to Dieppe crossing was also added to the IPS sample from October 2014.

Notes to tables and figures

The following conventions have been used in the tables:

0 denotes a figure of less than 0.5

. indicates that data are not available

The sum of spending across sub-categories of visit may not add to total spending. Spend per visit and spend per day by overseas visitors broken down by some categories of visit cannot be calculated by dividing spending by the number of visits. See Appendix B for details. In some cases, percentages in tables in this report from years prior to 2004 may differ by 1.0% from those published in previous years. This is because of changes in the method of rounding figures. The figures in this report are the most accurate.

Acknowledgements

The IPS is a large continuous survey and ONS would not be able to carry out the survey without the efforts of many different groups of people from a variety of organisations. In particular, ONS wishes to acknowledge the parts played by the following:

1. The interviewers for their role in collecting the information on which the results of the IPS are based.
2. The respondents for the information they have provided.
3. The operators and managers of seaports, airports and rail terminals who give IPS interviewers access to their facilities in order to interview passengers.
4. The companies and organisations that provide additional information and data which enable the IPS results to be produced.

Sample surveys such as the IPS depend on achieving high levels of response from the public. Non-respondents often have different characteristics of travel and expenditure compared with those who do respond and this can lead to biases being introduced into the results.

The response rates for the air, sea and the Channel Tunnel samples are shown in Table D.1. These response rates relate to complete and partial interviews. The overall response rate in 2015 was 78.4%. Information about the construction of the IPS overseas travel and tourism response rates can be found in the IPS Overseas Travel and Tourism User Guide (Volume 1): Background and Methodology. For information about the 2015 response rates contact socialsurveys@ons.gov.uk.

1. Annual figures shown in this publication are final estimates, previous estimates provided in the monthly and quarterly publications are provisional and subject to revision in light of additional passenger data obtained at the end of each year.

IPS estimates are revised in line with the IPS revisions policy. The revisions policy is available in the IPS Quality and Methodology Information report paper to assist users in the understanding of the cycle and frequency of data revisions. Users of this report are strongly advised to read this policy before using this data for research or policy related purposes.

Planned revisions usually arise from either the receipt of revised passenger traffic data or the correction of errors to existing data identified later in the annual processing cycle. Those of significant magnitude will be highlighted and explained.

Revisions to published quarterly IPS estimates can be expected in the publication of the annual overseas travel and tourism report (Travel trends).

All other revisions will be regarded as unplanned and will be dealt with by non-standard releases. All revisions will be released in compliance with the same principles as other new information. Please refer to the ONS guide to statistical revisions.

1. The main series are seasonally adjusted. This aids interpretation by identifying seasonal patterns and calendar effects and removing them from the unadjusted data. The resulting figures give a more accurate indication of underlying movements in the series.

2. The estimates produced from the IPS are subject to sampling errors that result because not every traveller to or from the UK is interviewed on the survey. Sampling errors are determined both by the sample design and by the sample size - generally speaking, the larger the sample supporting a particular estimate, the proportionately smaller is its sampling error. The survey sample size is approximately 70,000 per quarter.

Table E1 shows the 95% confidence intervals for the 2015 estimates of the total number of visits, nights and expenditure for both overseas residents visiting the UK and UK residents going abroad. These represent the interval into which there are 19 chances out of 20 that the true figure (had all travellers been surveyed) would lie.

If, for example, the relative 95% confidence interval relating to an estimate of 10,000 was 5.0% there would be 19 chances out of 20 that the true figure (if all travellers had been surveyed) would lie in the range 9,500 to 10,500.

The confidence intervals dataset for 2015 shows estimates relating to various purposes for visit and region of the world, together with regions of the UK visited. Relative confidence intervals are also shown for estimates relating to individual country of visit to and from the UK.

Further guidance for readers is provided about the quality of overseas Travel & Tourism estimates.

One indication of the reliability of the key indicators in this release can be obtained by monitoring the size of revisions. The monthly statistical bulletin provides information about the size and pattern of revisions to the quarterly IPS data which have occurred over the last 5 years to the following key seasonally adjusted estimates:

• the number of visits by overseas residents to the UK (GMAT)
• the number of visits abroad by UK residents (GMAX)
• earnings made from overseas residents in the UK (GMAZ) and
• expenditure abroad by UK residents (GMBB)

Statistical series are affected by special events. However, as explained in ONS's special events policy, it is not possible to make an estimate of the effect of particular events only on the basis of information collected in those series. However, we publish a special events calendar which may help the reader put some context on reported estimates.

IPS results published by ONS

In addition to Travel trends, we also publish provisional monthly and quarterly results from the IPS that are available free of charge from our website.

The website also provides more information about the International Passenger Survey methodology including the current IPS questionnaire and interviewer instructions.

Accessing datasets

1. To enable easier examination of the IPS data, a simplified version of the IPS dataset called Travelpac, comprising 14 of the most widely used variables, is available on our website. Data are available online for each year from 1993 onwards, in both SPSS and Excel formats.

2. Larger IPS datasets are available through the Data Archive at Essex University. Contact details are as follows:

Telephone: +44 (0) 1206 872143

Web: Data Archive Homepage

Other analyses

General enquiries about the IPS or requests for ad-hoc analyses should be directed to:

Office for National Statistics,
Data Advice Relations Team,
Room 2201,
Government Buildings,
Cardiff Road,
Newport.
NP10 8XG

Telephone: +44 (0)1633 455678

E-mail: socialsurveys@ons.gov.uk

1. Contact Details

General IPS queries and requests

For general questions about IPS and user requests for data analysis (a service governed by the ONS Income and Charging policy):

Tel: Data Advice Relations Team: +44 (0)1633 455678

Email:< socialsurveys@ons.gov.uk>

Statistical contact

For information about the content of this publication:

Tel: +44 (0)1633 455731

Email: socialsurveys@ons.gov.uk

1. Details of the policy governing the release of new data are available by visiting the UK Statistics Authority website.