Which explanation should be considered first when interpreting an observed association in a cohort or case-control study? (choose one best answer) Group of answer choices The observed association may be due to problems in study design which result in selection bias and/or information bias and thus the association is spurious. The observed association may be due to a third factor that is closely related to both the exposure and the disease in the study population. The observed association may be causal (exposure causes disease). The observed association may be due to chance alone