The NZHTS dataset analysed in this report includes travel by approximately 35,000 people from some 12,800 households in sample areas throughout New Zealand between 2003 and 20010. The NZHTS is administered by an independent contractor, on behalf of MoT, who sends selected households an initial letter which includes a pamphlet briefly describing the aims and content of the survey.
The interviewer then calls at the address to gather household information, explains the purpose of the survey and informs the household which days are their ‘travel days’. The travel days are two consecutive days for which the household records all travel. The two consecutive days may be two consecutive weekdays or weekends. An even spread according to the day of the week is maintained by systematic allocation of travel days. The survey includes trips beginning between 4am on day 1 to 3.59am on day 3, a 48-hour period. Respondents are given a memory jogger to use for recording travel. The survey is voluntary. The response rate calculated in 2003/2004 was 64% (MoT 2007).
Finally, the interviewer returns to conduct the interviews as soon as possible after the travel days. A detailed description of the NZHTS methodology can be found on the MoT website.