How Large Is Too Large? The Issue of Sample Size Requirements of Regional Household Travel Surveys, the Case of Transportation Tomorrow Survey in the Greater Toronto and Hamilton Area

The paper presents an analytical investigation on the requirements of household travel survey sample sizes, with a case study on the Greater Toronto and Hamilton Area (GTHA). A review of current practices reveals that different perspectives and, as a result, different practices exist in Canada, US and abroad on this issue. The paper focuses on the Canadian context for empirical investigation and investigates various aspects of large sample household travel surveys in the GTHA. It reveals that even with a 5% sample size, a full (more than 95 % confidence) representation of the population and their corresponding travel behaviour may be difficult. The paper proposes a flexible framework for household travel survey sample size determination for the Canadian municipalities.