COLLAPSE
In this unit you are thinking about bivariate distributions. One important feature of these distributions is covariance which ultimately establishes whether the two variables tend to "move together positively," "move inversely," or have no relationship (independent.) For this discussion please think about two examples with two quantitative, continuousvariables. In your first example, please choose (and describe) two variables that might have a non-zero covariance and in your second example discuss two variables you think would be independent (cov = 0).
(1) X1--the attendance at an Orioles baseball game; X2- the number of hotdogs sold at an Orioles baseball game
In this first example I would expect these two random variables to move together (and positively) as the attendance at a game increases, I would expect the number of hot dogs sold also to be higher.
(2) X1--the temperature; X2--the number of ice cream cones sold at store
SURPRISINGLY! In my yoga class at the gym there is a woman who owns an ice cream store. She amazed us all by telling us that they actually find no relationship between the termperature and the amount of ice cream they sell. [Note that this store is closed from October through March.] It is really interesting that there is not a positive relationship as I would have expected that more ice cream would be sold in hotter weather.