BIOS 1500 Lecture Notes - Lecture 9: Odds Ratio, American Broadcasting Company, Confidence Interval
Document Summary
This design gathers information in a single sample, at a single point in time. Information or assessment for all variables is obtained at this time. The design is: observational, non-directional or ambi-directional, and the timing is retrospective. It provides information on association between variables, not cause and effect. There is no randomization to groups and no intervention to influence the (cid:494)dependent(cid:495) variable: hence observational. Both the independent and dependent variables were assessed simultaneously (giving the non-directional aspect). The events being assessed are current or in existence when the study is executed. (the retrospective aspect). The count in each cell, and each marginal count in the contingency table is an unknown. The only known part in the table is the total sample size n. In the slides that follow, the red values are those that are obtained by sampling and the green are those known from the design component. The only quantity known by design is the total sample size n.
