Reliability, validity, and methodological issues in assessing physical activity in a cross-cultural setting

In summary, to complement the issues raised in Dr. Kriska's paper, this paper identified a number of methodological issues that researchers need to address before valid cross-cultural comparisons can be performed (see summary of issues and proposed actions for researchers in Table 1). In addition, this paper cautions us to interpret published findings in light of the methodological issues that were raised in this paper. This paper selectively addressed some methodological issues and leaves ample room for other researchers to think of other important issues. Many of the issues raised in this paper are related to the use of questionnaires to make cross-cultural comparisons. However, many of the methodological issues presented in this paper apply to other methods of assessing physical activity behaviors. As a final remark, I do want to acknowledge that other methods used to measure physical activity (including activity monitor) provide valuable but different information than questionnaires. It remains that in large-scale epidemiological studies, questionnaires are often the most practical instrument to use, and given the errors associated with questionnaires, we need to consider whether questionnaires are better at measuring physical activity behaviors at the group level or individual level.