How Large is too Large? A Review of the Issues related to Sample Size Requirements of Regional Household Travel Surveys with a Case Study on the Greater Toronto and Hamilton Area (GTHA)

TL;DR

This paper reviews sample size issues in regional household travel surveys, compares international practices, and uses data from the GTHA to assess sample adequacy, proposing a flexible framework for Canadian municipalities.

Contribution

It provides a comprehensive review of sample size practices and introduces a new flexible framework tailored for Canadian regional household travel surveys.

Findings

5% sample size may not fully represent population travel behavior

Current practices vary significantly across countries

Proposes a flexible sample size determination framework

Abstract

The paper presents a review of sample size issues related to regional household travel surveys. A review of current practices reveals that different perspectives and, as a result, different practices exist in Canada, US, and abroad on sample size. The paper uses data from the Transportation Tomorrow Survey (TTS) - a household travel survey conducted every five years in the Greater Toronto and Hamilton Area (GTHA) - for a set of empirical investigations that asses the adequacy of household travel survey samples. The empirical investigations reveal that even with a 5% sample size, a full representation of the population and its corresponding travel behaviour may be difficult (at the 95% confidence level). Therefore, based on the results of the empirical investigations and the literature review, the paper proposes a flexible framework for household travel survey sample size determination, especially for Canadian municipalities.