1.10.D—Identify an observational study

Identify an observational study.

• An observational study is a study where treatments are not imposed. The researcher records the values of the variables of interest in order to explore an investigative question of interest.
• A prospective study is one in which the observational units of study are selected at a point in time, and data are gathered both at that time and into the future.
• A retrospective study is one in which the observational units of study are selected at a point in time and data from the past are gathered.
• A survey is an observational study in which the data are collected from humans using a standard set of questions.
• A confounding variable in an observational study provides an alternative explanation for the observed relationship between the explanatory and response variables determined in the study, thereby reducing the possibility of concluding a causal relationship between the explanatory and response variables of interest. To be a confounding variable, a variable must be associated with both the explanatory variable and the response variable.