Distributions of changes in reported physical activity by time between first and repeat baseline questionnaires. Shaded regions indicate proportions of women reporting a frequency of physical activity on their repeat baseline questionnaire that was the same as, more than, or less than they reported at first administration. Women are stratified by the time between their first and repeat responses to the baseline questionnaire.
Armstrong et al. BMC Medical Research Methodology 2011 11:97 doi:10.1186/1471-2288-11-97