Each year on the National Travel Survey (NTS) about 7 per cent of households in the initial sample participate in some but not all parts of the survey. They are known as partially responding households. In recent years, data from these households have not been used in any way. The rate of full co-operation has fallen steadily throughout the 1990s, while the rate of partial reponse has remained roughly constant. The response rate in 1998 was 65 per cent, compared with 80 per cent in 1990. As a possible aid in tackling this problem, it was decided to investigate whether data from partially responding households could be included, to supplement the data from those households that co-operate in full. This paper is a summary of the analysis carried out. Most households that respond only partially do so as the result of one or more people failing to complete travel diaries. It is planned to include data from the partially responding households when the 2001 data are brought on stream. (A) For the covering abstract see ITRD E108997.
Samenvatting