In some earlier entries on this blog, I've posted stories about how money is related to (or can even change) people's social behavior, such as here and here. This week, the Washington Post ran a story about the association between money and socialization patterns. Let'sl= review the study, and you can have the chance to decide if the journalist made the right kinds of claims about the research.
The journalist first described how researchers Emily Bianchi of Emory University and Kathleen Vohs of the University of Minnesota tested the relationship between making money and socializing. People who make more money, they found, spend less time socializing with others:
Bianchi and Vohs...looked at nearly 30,000 responses to the General Social Survey (GSS) to trace how household income affects respondents' social interactions. The GSS has repeatedly asked Americans how often they spend a "social evening" with relatives, neighbors and friends. Those questions draw a fairly robust portrait of Americans' social interactions. Bianchi and Vohs controlled for age, race, gender, marital status, household size, city size and hours worked to isolate the effect of money on relationships.
a) What are the two key variables in the basic association?
b) The language used above, "controlled for" should tell you that they also analyzed the data using multiple regression. First, why was it important to control for variables such as "hours worked"?
c) Sketch out what the regression table might have looked like in their study. What would the dependent, or criterion variable, have been? What would the predictor variables have been? What will the beta be for "income"? Will it be positive or negative? Which other betas do you think will be significant, and what will their direction be? (You can make up some betas for your table to match your predictions.)
Next, here's an indicator of the effect size of the relationship:
Compared to a low-income individual (earning $5,000 a year), a person from a higher-income household ($131,000 a year) spends, on average, 6.4 fewer evenings each year socializing with other people — even after controlling for differences in hours worked.
d) What do you think of the practically-stated effect size of "6.4 fewer evenings per year"? Does that seem small or large, in a practical sense?
Now, here are some of the sentences included in the story that were used to describe the results. For each one, decide if it is a causal statement or an association statement (remember to attend to the verbs!):
e) "How money changes our social networks"
f) "Inflation-adjusted household income has risen considerably since the World War II era (even if it's been fairly stagnant in the past decade). And if the relationship between income and social behavior they describe is true, then it's only natural that decreasing social interactions will be one consequence of that change."
g) "as people make more money, they spend less time socializing with others"
As you have learned, a correlational study like this one, even though it controlled for several possible third variables, cannot support a causal claim. For one, there may not be temporal precedence because in surveys like the General Social Survey, people usually answer all the questions at the same time. In addition, there are always uncontrolled third variables that the study did not measure or include in the regression. What possible third variables can you think of that might be associated with both having money and socializing less?