What you’ll learn to do: Identify features of experiment design that control the effects of confounding.
In experiments, instead of assessing the values of the variables as they naturally occur, the researchers interfere and they are the ones who assign the values of the explanatory variable to the individuals. The researchers “take control” of the values of the explanatory variable because they want to see how changes in the value of the explanatory variable affect the response variable. (Note: By nature, any experiment involves at least two variables.)
The type of experiment design used, and the details of the design, are crucial, since they will determine what kind of conclusions we may draw from the results. This is especially important when we are trying to establish a cause-and-effect relationship between two variables.