February 5, 2004
When she first started to study the impact of binge drinking on college students' grades, Bucknell University economist Amy Wolaver thought the project would be a "no-brainer."
She thought she'd find that heavy, episodic drinking would lower grades significantly. She also thought that alcohol's impact on women's grades might be greater than its impact on men, for various physiological, psychological, and sociological reasons.
"But it's not a no-brainer," says Wolaver, assistant professor of economics at Bucknell. In the end, Wolaver found only a "very small" difference in the impact of drinking on men's and women's grades. "There is an impact on grades: It's pretty much the same for men and women, although they do behave differently."
The shocker for Wolaver was her finding that alcohol's negative impact on earnings immediately after graduation "is greater for women, even though the impact on grades is virtually the same."
To tease out the effects of binge drinking on grade-point averages (GPA), Wolaver used a sophisticated regression analysis involving many variables. She calculated that the effective of binge drinking for both men and women college students is very close — a drop of about a third of a point in GPA.
Wolaver found that women who do not binge have a "predicted GPA" of 3.29, compared to a 3.01 GPA for women who binge. Men who don't binge have a predicted GPA of 3.25; for those who do binge, it's 2.95.
Thus, the impact of binge drinking for women is 0.28 of a point in predicted GPA; for men, the drop in predicted GPA is 0.30.
However, the impact on subsequent earnings is striking. For women who binge drink, Wolaver found a 4.2 percent drop in annual earnings, or about $1,600 a year. For men, there was a 0.47 percent drop, or about $235 a year.
Wolaver says her study shows that "there is some role for economics in predicting behavioral differences" in drinking among men and women and believes that her findings could help colleges and universities design effective policies to discourage binge drinking.
Wolaver established a link between alcohol and salaries by linking her binge drinking data with data from a labor market study that demonstrates a positive relationship between college GPA and the earnings of college graduates in their first jobs after graduation. According to the labor market study, the higher the GPA, the higher the earnings.
When Wolaver plugged her findings into the labor market study, it translated into substantially lower annual salaries for women who binge in college, and slightly lower annual salaries for men who binge.
"The impact on salaries is very different for men and women, because the labor market treats the grade-point averages of men and women differently," she says.
Even though heavy drinking has a similar impact on grades for men and women, Wolaver concludes, they "may behave differently not because of biological differences in alcohol's effects, but because of different penalties for behavior after college."
In her study, Wolaver used 1993 and 1997 data from Harvard's nationwide study of college student drinking habits. The Harvard survey is meant to be nationally representative. But Wolaver cautions that her study used only 1993 and 1997 data, and also notes that a number of schools dropped out of the study during that period.
Wolaver also notes that the Harvard definition of binge drinking has been controversial — five or more drinks on one sitting for men, four or more drinks on one sitting for women. She also lists several general differences in women's and men's behavior, as it relates to education and drinking, including:
Still, Wolaver is confident of her results. Soon after she began the study, she found that she had to look at the data very carefully to avoid confusing simple correlations (for example, links between grades, study hours, and drinking) with cause and effect. Just because two things are linked, she says, doesn't necessarily mean that one causes the other.
Wolaver's analysis also had to be extremely sophisticated in order to account for different kinds of "bias" that could have skewed the results of the study and made them inaccurate.
Some of Wolaver's research in this area was published in the October 2002 issue of "Contemporary Economic Policy," Vol. 20, No. 4.