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Background Notes

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Purpose of Survey

The National Travel Survey (NTS) is a household survey on the travel behaviour of respondents. It was conducted in the fourth quarter (October – December) of 2019 as part of the General Household Survey (GHS). A similar survey was carried out most recently in 2016 and prior to that in 2012, 2013 and 2014 as a module of the Quarterly National Household Survey (QNHS).

The NTS will be used to compile statistical indicators for journey purpose and modes of travel, which will help monitor the implementation of existing transport policy and will inform future transport initiatives.

Survey Design

In 2019, the NTS was carried out as part of the General Household Survey (GHS). The GHS is a national survey that place takes place three or four times each year. The survey usually has a core of common demographic questions that are always asked (e.g. age, sex, education, etc.). Each survey also has a specific theme. In the fourth quarter of 2019, the GHS covered the National Travel Survey.

Here below are the topics covered in the GHS so far:





Quarter 3 and Quarter 4

Adult Education Survey 


Quarter 1

Information and Communications Technology (ICT)


Quarter 3 and Quarter 4

Household Finance and Consumption Survey 2018


Quarter 1

Information and Communications Technology (ICT) 


Quarter 1

Equality and Discrimination 2019


Quarter 2 and Quarter 3

Crime and Victimisation


Reference Period

The National Travel Survey for the reference year 2019 was included in the GHS in the three months from October to December 2019 (Quarter 4). The travel reference days, i.e. the days for which travel data was collected, covered the period October 7th 2019 – January 5th 2020.


The NTS questionnaire was designed by the Central Statistics Office in consultation with the Department of Transport, Tourism and Sport (DTTS), the National Transport Authority (NTA) and the Road Safety Authority (RSA).

A copy of the NTS 2019 questionnaire is available on the CSO website at: National Travel Survey 2019 Questionnaire (PDF 405KB)

Individual Reference Person

This survey was asked of persons aged 18 years and over. Only direct respondents were included in the NTS survey (i.e. no third party responses were permitted).

Data Collection

The data was collected by a team of up to one hundred Field Interviewers and ten Field coordinators (each with a team of ten interviewers). Interviewers were provided with a map of each of their interview areas, as well as a listing of the address of each of the selected households. These interviewers also work on CSO surveys such as the Survey on Income and Living Conditions and the Labour Force Survey. Interviewers received a manual with information such as detailed explanations about the questionnaire, definitions of the concepts involved and examples.

It was conducted using a team of face-to-face interviewers using Computer Assisted Personal Interviewing (CAPI). This enabled the use of extensive checks in the BLAISE interviewing software to make sure correct and coherent data was collected.

One person from each household was selected. Information was collected directly from respondents - proxy responses from other members of the household were not accepted.

Survey Coverage

The NTS data is collected directly from persons residing in private households. Institutional households, (e.g. nursing homes, barracks, boarding schools, hotels etc.) are not covered by the survey.

A household is defined as a single person or group of people who usually reside together in the same accommodation and who share the same catering arrangements. The household members are not necessarily related by blood or marriage.

A person is defined as a "Usual Resident" of a private household if he or she:

  • Lives regularly at the dwelling in question, and
  • Shares the main living accommodation (i.e. kitchen, living room or bathroom) with the other members of the household.

Sample Design

The sample for the General Household Survey (GHS) is stratified using administrative county and the Pobal HP (Haase and Pratschke) Deprivation Index (quintile). A two-stage sample design is used. In the first stage 1,300 blocks are selected using Probability Proportional to Size (PPS) sampling. In the second stage households are selected using Simple Random Sampling (SRS). This ensures each household in the sample frame has an equal probability of selection.

The total sample size for the National Travel Survey in Q4 2019 was 8,400 households. The number of valid responding households was 3,650.

The survey results were weighted to agree with population estimates broken down by age, sex and region and are also calibrated to nationality totals.

Derivation of Results

To provide national population results, the survey results were weighted to represent the entire population of persons aged 18 years and over. The survey results were weighted to agree with population estimates broken down by age group, sex and region and were also calibrated to nationality totals.

Household weights were calculated for all households in the initial sample. The design weights are computed as the inverse of the selection probability of the unit. The purpose of design weights is to eliminate the bias induced by unequal selection probabilities.

These design weights were then adjusted for non-response. This eliminated the bias introduced by discrepancies caused by non-response, particularly critical when the non-responding households are different from the responding ones in respect to some survey variables as this may create substantial bias in the estimates. Design weights are adjusted for non-response by dividing the design weights of each responding unit in the final/achieved sample by the (weighted) response probability of the corresponding group or strata.

To obtain the final household weights for the results, after the previous steps were carried out, the distribution of households by deprivation, NUTS3 region, sex and age was calibrated to the population of households in Quarter 4 2019 (as derived from the LFS Survey). The CALMAR2-macro, developed by INSEE, was used for this purpose.

Note on Tables

The sum of row or column percentages in the tables in this report may not add to 100.0% due to rounding.

Percentage breakdowns exclude cases where the interviewee did not respond.

Disclosure Control

Estimates for number of persons where there are less than 30 persons in a cell are too small to be considered reliable. These estimates are presented with an asterisk (*) in the relevant tables.

Where there are 30-49 persons in a cell, estimates are considered to have a wider margin of error and should be treated with caution. These cells are presented with parentheses [ ].

In the case of rates, these limits apply to the denominator used in generating the rate. In the case of annual changes, both the current year and the preceding year are taken into account when deciding whether the estimate should be suppressed or flagged as having a wider margin of error.

Reliability of Estimates Presented

Data are subject to sampling and other survey errors, which are relatively greater in respect of smaller values.

Guide to Using NTS Results

Care should be taken when interpreting the results or when comparing them with other data sources such as POWSCAR. POWSCAR is the 2016 Census of Population Travel to Work, School and College Census of Anonymised Records and is available at the following link Census 2011 Place of Work, School or College - Census of Anonymised Records (POWSCAR). POWSCAR should be used as the definitive source of data on travel to work, school and college. When comparing the NTS results to POWSCAR data, it should be noted that the NTS journey purpose of ‘work’ includes both commuter and business travel, while the POWSCAR data includes commuter travel only. The NTS collected travel data for a specific day while the Census collected travel data for the ‘usual’ journey to work, school or college. Similarly, when examining issues such as the mode share for travel to school/education, it is important to note that the NTS doesn't accurately reflect the mode share for the whole student population as the NTS only sampled persons aged 18 years and over.

Data from other international sources/surveys indicates that there can be significant seasonal variations in travel patterns. The NTS travel reference days spanned the Christmas and New Year holiday period when travel patterns may be atypical. This period also encompasses the shortest days and some of the coldest and wettest weather of the year. Estimation of survey results from data relating to only one day’s activity for a sample of journey introduces a statistical variability which would not be present if a full year’s data had been collected.

Key Definitions and Descriptions


This survey was asked of adults, aged 18 years and over, resident in the Republic of Ireland.


A journey is defined as a one-way course of travel from location A to location B for the purpose of carrying out a specific activity at location B. A location could be a single premise (e.g. a house, an apartment, a shop, an office, etc.) or a complex of premises (e.g. a shopping centre, a factory site, a hospital, etc.). Return trips were recorded as separate journeys. To be relevant to the survey, journeys must have:

Commenced in the travel reference day (it may end the following day)

Been at least 100 metres in length (approximately a one minute walk)

Comprised exclusively of domestic travel (all stages of foreign travel were excluded)

Not formed an integral part of a respondent's routine employment (e.g. milkman, taxi driver, etc.)

Journey Purpose

The purpose of a journey is governed by what action was taken at the end of the journey.

Mode of Travel

Where a journey consists of more than one mode of travel, the main mode of travel is determined by the mode of travel used for the greatest distance. In the event of there being more than one main mode of travel (i.e. when two or more modes are of equal distance), then the main mode of travel is determined by the mode of travel used for the earliest stage of the journey.

Journey Duration

This is calculated as the sum of time spent on each stage of the journey and not the difference between the start and end time of a journey.

Travel Reference Period

The travel reference period is 4am to 3:59am. This allowed the capture of information for respondents who finish work or return from leisure activities after midnight.

Travel Reference Day

To ensure that data was collected for all seven days of the week, each person participating in the NTS was assigned a selected 'travel reference day'. The travel reference day was a maximum of three days prior to the day on which the interview was conducted to ensure that recall was not compromised.

For interviews conducted on Wednesday through to Saturday, the travel reference day was the immediately preceding day, i.e. if a person was interviewed on Friday November 22nd, the travel reference day would be Thursday November 21st.

For interviews conducted on Mondays a different arrangement applied. 30% of Monday interviews were assigned at random to the immediately preceding Friday, 42% to the immediately preceding Saturday and 28% to the immediately preceding Sunday.

For interviews conducted on Tuesdays, 17% were assigned at random to the immediately preceding Sunday and 83% were assigned to the immediately preceding Monday.

Degree of Urbanisation

This classification is created from an aggregation of population density estimates derived from the Census of Population. The categories included in each aggregate are explained below:

  • Thinly populated area refers to rural areas
  • Intermediate density area refers to towns and suburbs
  • Densely populated area refers to cities, urban centres and urban areas


The regional classifications in this release is based on the NUTS (Nomenclature of Territorial Units) classification used by Eurostat. Until Q4 2017, the NUTS3 regions corresponded to the eight Regional Authorities established under the Local Government Act, 1991 (Regional Authorities) (Establishment) Order, 1993, which came into operation on 1 January 1994 while the NUTS2 regions, which were proposed by Government and agreed by Eurostat in 1999, were groupings of those historic NUTS3 regions.

However, the NUTS3 boundaries were amended on 21st of November 2016 under Regulation (EC) No. 2066/2016 and have come into force from Q1 2018. These new groupings are reflected in the LFS results from Q1 2012 onwards. The changes resulting from the amendment are that County Louth has moved from the Border to the Mid-East and what was formerly South Tipperary has moved from the South-East to the Mid-West, resulting in the new NUTS2 and NUTS3 regions:

NUTS2 Code
NUTS2 Name
NUTS3 Code
NUTS3 Name
Northern & Western
Eastern & Midland 


The Central Statistics Office wishes to thank the participating households for their co-operation in agreeing to take part in the National Travel Survey and for facilitating the collection of the relevant data.

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