Types of Variables Explanatory Variable Response Variable Lurking

Types of Variables • Explanatory Variable: • Response Variable: • Lurking Variable: Cause in a Cause-Effect Relationship Usually Directly Controlled/Changed Independent Variable Effect in a Cause-Effect Relationship Usually Indirectly Controlled/Changed Dependent Variable Any variable that wasn’t measure but has an affect on the response variable

Exploring Cause & Effect • Causation, you’re looking at 2 variables: x & y and x causes y. X Explanatory Variable Y Response Variable

Exploring Cause & Effect • Common Response, you measure 2 variables which are caused by the same unmeasured variable. X Y Response Variable Z Lurking Variable

Exploring Cause & Effect • Confounding, you measure 2 variables, x & y. X causes Y, but it is not the ONLY variable that affects Y. Y Response Variable X Explanatory Variable Z Lurking Variable

Causation, Common Response or Confounding? • Person’s height vs. distance from fingertip to fingertip Common Response • Smoking vs. Lung Cancer Confounding • Education vs. Career Salary Confounding • Bounce height of a new Penn tennis ball dropped inside on a hard surface and drop height Causation, all (if not most) lurking variables have been accounted for. In life it can be rather difficulty to account for all lurking variables

Causation, Common Response or Confounding? • As a class do page 188, #4. 39, 4. 40, 4. 42