To investigate whether there is an association between happiness and income level, we will use data from the 2002 General Social Survey (GSS), cross-classifying a person’s perceived happiness with their family income level. The GSS is a survey of randomly selected U. S. adults who are not institutionalized. Here are the data:

a. Identify the explanatory variable. Is it a categorical variable or a quantitative variable?

b. Identify the response variable. Is it a categorical variable or a quantitative variable?

c. Among above-average-income individuals 0.379 are very happy (110/290); among average income individuals 0.342 are very happy (221/646); and, among below-average- income individuals 0.195 are very happy (83/426). Do the data provide any indication of an association between happiness and income level? Why or why not?

d. Is it okay to conclude that income affects happiness? If yes, explain why. If no, then identify a confounding variable that provides an alternative explanation for the associa- tion between happiness and income level.