STAT 111 Lecture Notes - Lecture 2: Confounding, Dependent And Independent Variables, Randomized Experiment

• School: University of Vermont
• Department: Statistics
• Course: STAT 111
• Professor: Jacob William Martin

Document Summary

2 variables are associated if values of one variable tend to be related to values of another. 2 variables are causally associated if changing the value of the explanatory variable influences the value of the response variable. Observational study: a study in which the researcher does not actively control the value of any variable, simply observe the values as they naturally exist. Experiment: study in which the researcher actively controls one of the explanatory variables. Observational studies: there are almost always confounding variables in observational studies, can almost nevr be used to establish causation. Randomization: avoid confounding variables, randomly assign values of the explanatory variable. If treatments are randomly assigned, the treatment groups should all look similar: because the explanatory variable is randomly assigned, it is not associated with any other variables, confounding variables influences are eliminated. If a randomized experiment yields a significant association between the 2 variables, we can establish causation from the explanatory to the response variable.