could be improved in future studies.22,23 Contacting subjects by telephone first, rather than by letter, seems to help. More follow-up attempts with subjects who have been contacted but have not returned their questionnaires would likely improve participation.
et des personnes issues de la population de recensement étaient mariés ou vivaient en union de fait, et près des trois quarts des sujets dans les deux cohortes travaillaient à temps plein ou à temps partiel.