The denominators are the weighted total number of individuals in each ethnic group. The numerators are the weighted total distance of travel, or number of trips, by different types of transport and for different purposes for each ethnic group.
The NTS data collection consists of a face-to-face interview and a 7-day self-completed written travel diary, allowing travel patterns to be linked with individual characteristics. The NTS covers travel by people in all age groups, including children.
In 2013, the survey coverage changed from sampling residents of England, Wales and Scotland, to residents of England only. Approximately 16,000 individuals in 7,000 households in England participate in the NTS each year.
Weighting is used to adjust the results of a survey to make them representative of the population and improve their accuracy.
For example, a survey which contains 25% women and 75% men will not accurately reflect the views of the general population, which has an even 50/50 split.
Statisticians rebalance or ‘weight’ the survey results to more accurately represent the general population. This helps to make them more reliable.
Survey weights are usually applied to make sure the survey sample has broadly the same gender, age, ethnic and geographic make up as the general population.
Responses to the NTS are weighted to take account of different population demographics, but are not grossed to England totals. They are also weighted to take into account people who didn’t respond or didn’t complete their travel diary in full.
Statistics from the NTS were assessed during 2010 by the UK Statistics Authority. An assessment report was published in October 2010. The statistics were confirmed as National Statistics in July 2011.
Suppression rules and disclosure control
Values of fewer than 100 people or 300 trips (before weighting is applied) have been suppressed. ‘Suppression’ means the figures have not been included in the data, because the numbers involved are too small to draw any meaningful conclusions.
For example, in the latest 5-year period, there were only around 700 and 900 individuals in the 'Mixed' and 'Other' ethnic groups respectively, so the data does not support further detailed breakdowns as these estimates would be unreliable.
Where the size of the ethnic group population is small enough that an individual’s identity could be revealed, some other figures have also been excluded.
Figures are rounded to the nearest whole percentage. The percentages calculated in the tables are based on unrounded figures.
Previous National Travel Survey reports are available.Quality and methodology information