2. Background
2.1 This bulletin provides information, collected by the Scottish Household Survey ( SHS), which started in 1999, about travel by a random sample of adults (aged 16+) living in private households across Scotland. Statistics are provided for Scotland overall, for local authority and Regional Transport Partnership area, and for each category of an urban/rural classification which was developed for use in analysing the results of the SHS. The topics covered include the days of the week on which people travel, the means of transport used by different types of people, the purposes for which people travel, the distances that they go, the times of day at which trips start, the duration of journeys, the number of occupants for trips made as the driver of a car, delays due to congestion to car journeys, delays to bus and rail journeys, whether a car driver paid for parking, and the types of shopping journeys. All this information is obtained from interviews with one randomly-chosen adult per household in the sample. This person is asked about his/her travel on the day prior to the interview. Each adult in the household has an equal chance of selection for these questions. The information about the person's travel is analysed in conjunction with data collected by questions about the household as a whole, which are answered by either the Highest Income Householder (please see paragraph A3.6 of the "Notes and Definitions", which appear after the tables) or his/her spouse/partner.
2.2 The statistics given here were mostly extracted from the Scottish Executive's SHS database in January 2006, so will not take account of any subsequent revisions to the data ( e.g. due to improvements to the imputation process). The statistics for 1999 to 2003 may differ slightly from those published in previous editions of this bulletin because further data cleaning has been carried out and the imputation process has been re-run. The results have been weighted to take account of differences in selection probabilities. As with all such surveys, sampling variability and non-response bias may affect the results. It is particularly important to keep this in mind when looking at any results which are based on small numbers of cases in the sample, and especially when looking at the results for individual local authority areas, or some Regional Transport Partnership areas, because some of them may be affected by quite large percentage sampling errors. Section A7 provides information on the possible scale of sampling errors, and on other reasons why the SHS results may provide only broad indications for some types of people. Also, the figures for some local authority areas may be unrepresentative, because the interviewer(s) in those areas may conduct most of their interviews on certain days of the week. Although a reweighting process produces an even spread of interviews for Scotland as a whole, the distribution of reported journeys for some areas could depend greatly upon interviewing patterns as well as journeys made - see section A4.2 for more details.
2.3 The main changes from the previous edition of this bulletin are the inclusion of council and Regional Transport Partnership area tables on:
- day of week of journey;
- main mode of travel;
- journey purpose ; and
- journey distance.
In addition, now that six years' data are available, nine "trend" tables A to I have been added, on the following topics;
- main mode of travel;
- journey purpose;
- journey distance (two tables);
- journey start time;
- duration of journey;
- car occupancy;
- adults who reported travelling; and
- day of week of journey.
More information on the Regional Transport Partnership areas is given in section A6.5 of the text. The names given of the Regional Transport Partnership areas were those that applied at the time of this bulletin going to print.
2.4 In order to make room for the new tables mentioned above, some of the tables which appeared in the previous edition have been omitted from this edition. These were tables on "specialist" topics, which were based on the data for all the years in which the survey was conducted, whose results would not be changed much by the use of a further year's data. Annex 2 lists the tables from previous editions which are not in this edition.
2.5 Since its introduction, this bulletin has appeared annually. However, many of the figures it provides do not change much from year to year (apart from the inevitable fluctuations due to sampling variability). Therefore, it has been decided, following consultation with the Transport and Travel Statistics Advisory Committee, that this bulletin should henceforth appear biennially. The next edition will therefore be " SHS Travel Diary results for 2005 and 2006", and will be scheduled for publication by March 2008.