title: Invited commentary: hypothetical interventions to define causal effects--afterthought or prerequisite?
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA. miguel_hernan@post.harvard.edu
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Hernán
mesh_terms: D015502:Absorptiometry, Photon; D000203:Activities of Daily Living; D000368:Aged; D000375:Aging; D000886:Anthropometry; D001823:Body Composition; D002140:California; D015984:Causality; D017097:Electric Impedance; D015444:Exercise; D005260:Female; D006304:Health Status; D006801:Humans; D007899:Leisure Activities; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D013269:Stochastic Processes; D011795:Surveys and Questionnaires