This report provides information on the quality of the data used to produce the official statistics in the following DfI publications from the YPBAS Survey:
The report is structured around the five quality dimensions for statistical outputs (from the European Statistics Code of Practice, PDF (458 KB). The UK Statistics Authority’s Code of Practice for Statistics requires that:
6.7 Base methods on national or international good practice, scientific principles or professional consensus. Identify potential bias and address limitations. Use recognised standards, classifications and definitions. Explain reasons for deviations from these standards and any related implications for use.
6.10 Verify that the statistics are representative and of suitable quality and monitor relevant quality dimensions for both input data and the statistics, such as completeness and validity, accuracy and reliability, coherence and comparability, and timeliness. Quantify statistical error, including bias, and produce measures of confidence, where possible.
7.2 Report on the key quality dimensions such as accuracy and timeliness, and, where possible, give estimates of error and confidence for the statistics. Summarise how uncertainty in the estimates may impact use by using qualifying words, numbers or graphics.
The Young Persons’ Behaviour and Attitudes Survey (YPBAS) is a school-based survey carried out amongst 11-16 year olds and covers a wide range of topics relevant to the lives of young people today. The main aim of the YPBAS is to gain an insight into, and understanding of, their behaviour and lifestyle.
The survey is administered by Central Survey Unit of the Northern Ireland Statistics and Research Agency (NISRA). The YPBAS has been running triennially since 2000. Nine rounds of the survey have now taken place: 2000, 2003, 2007, 2010, 2013, 2016, 2019, 2022 and 2025.
The Department for Infrastructure (DfI) commissions modules in the survey and the findings are used to inform and assist in future policy development.
For each cycle, CSU requests updates to the content of the questionnaire modules or proposed new modules, in consultation with client departments.
In DfI, modules are reviewed each cycle to ensure continued relevance to Departmental Policy. This process is managed by statistical staff, who liaise with relevant policy managers to ensure suitable content is developed and that timescales and analysis outputs are understood and useful to policy customers.
For 2025 YPBAS DfI commissioned the module, “Travel to and from School” to capture information on the how far respondents live from school, how they travel to/from school, their preference of travel, if pupils feel safe travelling to school and what makes them feel unsafe or would encourage them to walk or cycle to/from school.
Data collection - The fieldwork for the 2025 YPBAS took place from September 2025 to February 2026.
A three-stage sample design was used:
Schools The Department of Education (DE) provided NISRA with a list of all post-primary schools in Northern Ireland (excluding independent schools and those which catered solely for pupils with special needs). All 190 post-primary schools were contacted and invited to participate, and the Department of Education were informed that schools were being approached. Follow up efforts were made to encourage non-responding schools to take part.
Classes Participating schools provided details of the number of classes in Years 8-12. One class in each of the five year groups was then randomly selected to take part in the study.
Pupils All pupils in each sampled class were selected for the survey. Once pupils in participating schools had been selected, they and their parents/guardians were notified of the survey in writing through the schools preferred method of parent/guardian communication (e.g. school app, printed letters). They were informed that participation was voluntary and that they could contact NISRA if they had any queries about the survey. If a selected pupil refused to participate or was absent on the day of the survey, no other replacement was accepted for that individual.
Unlike previous years, the data were collected online, using school computers which was available immediately on NISRA servers. Some schools requested the use of tablets as in previous years. In these instances, the data were collected using Microsoft Surface Tablets, and each machine was synced to send the data directly to a NISRA server once the survey day completed. In most instances, classes were surveyed sequentially, often in a classroom setting. Some schools requested that multiple or all classes be surveyed concurrently; in such cases, the survey was usually carried out in the school gym/assembly hall.
Response Rate – For the 2025 survey, all 190 post-primary schools in Northern Ireland were contacted and invited to participate, with 90 schools agreeing to participate in the study, accounting for 47% of all post-primary schools in Northern Ireland.
A total of 8,875 pupils aged 11 - 16 years took part in the survey. Three versions of the questionnaire were created to accommodate demand for topics on the 2025 survey. Each survey version was administered to an equal number of schools. Questions on travel to/from school were included in version C, which contained responses from 2,830 pupils.
Non Response Error/Bias and Weighting – In any survey there is a possibility of non-response bias. Non-response bias arises if the characteristics of non-respondents differ from those of respondents in such a way that they are reflected in the responses given in the survey. Accurate estimates of non-response bias can be obtained by comparing characteristics of the achieved sample with the distribution of the same characteristics in the population at the time of sampling. The non-response rates can be applied sequentially to calibrate the characteristics of the achieved sample to the school population distribution (from the 2025/2026 School Census, DE) in respect of year group, sex and religion. Once weighted, the achieved sample became more representative of the population the survey aimed to reflect.
DfI carry out checks on each module to determine whether weighting should be applied and each publication will inform the reader whether weights have been applied or not.
No sample is likely to reflect precisely the characteristics of the population it is drawn from because of both sampling and non-sampling errors. An estimate of the amount of error due to the sampling process can be calculated. For a simple random sample design, in which every member of the sampled population has an equal and independent chance of inclusion in the sample, the sampling error of any percentage, p, can be calculated by the formula:
s.e. (p) = √(p*(100 – p)/n
Where n is the number of respondents on which the percentage is based.
Since a three stage sample design was used in YPBAS: schools, classes and pupils, the required assumption of random sampling is not met. However, a methodological review conducted in 2013 which used a formula for complex samples to calculate standard errors for some of the variables in the survey showed that there was little difference to the precision of the estimates than when assuming a simple random sample. As sampling and post stratification methods have remained consistent on the survey, this is therefore assumed to still be the case and no design effect has been calculated.
A confidence interval for the population percentage can be calculated by the formula 95 per cent confidence interval:
95% confidence interval = p+/- 1.96 * s.e. (p)
If 100 similar, independent samples were chosen from the same population, 95 of them would be expected to yield an estimate for the percentage, p, within this confidence interval.
Given available resource in the Branch, ASRB aim to publish all DfI publications by the end of the financial year in which data are received. That is all data received from April 1st should have been analysed and published by the 31st March the following year. Order of publication is prioritised through liaison with policy customers and through ASRB’s understanding of departmental priorities.
For each module that DfI include on the YPBAS, a report or factsheet is published (in line with The Public Sector Bodies (Websites and Mobile Applications) (No. 2) Accessibility Regulations 2018) complete with infographics and data tables in both Excel and ODS format and these are published on the ASRB homepage:
https://www.infrastructure-ni.gov.uk/topics/dfi-statistics-and-research
The main report for each module contains a ‘Technical Notes’ section, outlining important information of the survey including data collection methods, an assessment of data quality, respondent information, information on weighting and other associated survey information.
Further information from the YPBAS is published on the NISRA website:
https://www.nisra.gov.uk/statistics/find-your-survey/young-persons-behaviour-attitudes-survey
The Travel to School Module this module was produced in conjunction with the ‘Travel to and from school’ from the Contiuous Household SUrvey (CHS) publication produced by the Analysis, Statistics and Research Branch (ASRB) in the Department for Infrastructure (DfI) which is available to view on the ASRB webpage. Travel to and From School
All surveys conducted by Central Survey Unit follow harmonisation guidelines produced by ONS. This means that, especially for demographic data, questions are asked in the same way and are therefore comparable.
Usually, where modules or questions have been asked in previous years of the YPBAS, the latest data are always compared with previous years’ data and any significant changes are thoroughly checked and validated.
The survey is conflicted with regard to demand for space on the questionnaire and the resultant burden that is placed on respondents.
It could be considered that there is some trade-off between ‘relevance’ and ‘accuracy and reliability’. The sample size of the survey means that sometimes limited analysis can take place for specific travel modes, geographic and other sub-population breakdowns.
YPBAS data are only analysed if the sample size is large enough for robust analysis.
Policy need also means that priorities can drive change in the modules and that leads to a trade-off between ‘relevance’ and ‘comparability’ as content can change year to year depending on what need exists. Time series can stop suddenly due to changing priorities.
Data presented in this report help to meet the information needs of a wide range of internal and external users (see “Relevance” section for more details of users and uses of the YPBAS reports and data). In addition to the reports, YPBAS data may be used to answer a number of ad-hoc queries throughout the year. Given the model employed to develop modules, user needs are discussed before every new survey round and module content developed to reflect that emerging need and how data already published has been used. Modules are then updated based on learning from those conversations.
ASRB have a mailing list of YPBAS users for each publication who are notified each time a relevant YPBAS publication is issued. This list was recently refreshed to ensure it is up to date and that the people on it still wish to receive information about a specific YPBAS publication, in consideration of GDPR requirements.
There is an on-going ASRB customer satisfaction survey which includes a question on whether ASRB publications meet customers’ needs. The link to the survey is issued every time users are notified that a report has been published or an ad-hoc query is answered. Results are collated on a quarterly basis. User needs are prioritised, taking account of resources available and the relevance and feasibility of any additional needs identified.
The overall cost of running the YPBAS cannot be provided as this is commercial-in-confidence.
DfI commissioned modules are designed to fulfill the Department’s data requirements. Consideration is taken to maximise the usefulness of the data whilst being mindful of the burden on respondents.
YPBAS data received by ASRB are anonymised (name/address information is not contained in the database). In addition, the data represent a sample of the population and there is no way for ASRB to identify the sample that was chosen from the population.
The data are held either on a secure and accredited network drive that is only accessible to ASRB staff or within DfI’s secure record management system, Content Manager (CM), also with restricted access and subject to standard record retention protocols.
Analysis is only carried out if the sample size is large enough and the data are presented as averages or percentages. There are therefore no small cells which need to have disclosure control methods applied. ASRB has produced a statement on its confidentiality processes which can be found in the Department for Infrastructure’s Code of Practice for Statistics supporting statements: