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The connection between high school GPA and future income: This graph seems too linear to be true.

favicon In today’s Washington Post, reporter Jonnelle Marte summarized a new study, conducted by researchers at the University of Miami, that indicates that there is a direct correlation between grade point average in high school and future annual income.

This conclusion isn’t earth-shattering. But take a look at this crazy graph:

GPA Future Income

Can this be true? Is it possible, really, for the relationship to be so intensely linear?

The researchers, including Michael T. French, director of the health economics research group, think so. They surveyed about 10,000 people in their early-30s and consulted high school transcripts to confirm grade point averages. For every point a GPA went up, men earned 12 percent more and women earned 14 percent more.

Side note: Not surprising that the graph above has two bars, one for men and one for women. As stark as the linearity of the graph is the earnings gap between men and women.

After getting over my initial shock, my second thought is whether to use this graph with students (and if so, how).

My gut says yes. You see, students, your grades really do matter! Look at this graph!

But a few things make me think twice. One concern is that students won’t think this data applies to them. Teenagers are notorious for thinking that they’re unique. Which of course they are. Even if I explained that the graph represents 10,000 unique individuals, students wouldn’t necessary buy it.

Another worry is the reverse: that students will believe that this graph represents cause and effect. “Mr. Isero, my GPA is 1.5. Are you telling me that all I can make is $30,000 a year? I might as well drop out.” Sometimes, provocative images and graphs can lead to negative consequences, no matter how much explanation a teacher offers.

One wish I have about this graph would be to add educational attainment into the mix. For example: What percentage of students with 1.5 GPAs have college degrees? What happens to your income if you have a 1.5 GPA and a college degree? What if you don’t get a college degree?

I’d love to hear your thoughts about this graph. Would you use it? If so, how? I can’t wait to read your brilliant insights! favicon

3 comments

  1. Sarah

    Holy Cow, Batman!!! If I earned a 4.0 in high school, then I earn as much as a guy who earned a 2.0? That doesn’t sound OK to me.

  2. Skeptic

    Is this household or individual income? The average us wage in the US was around $45K which suggests that most americans got 4.0’s in high school?!? That’s not right. This graph is VERY suspicious and VERY linear. Based on the comment, “for every point of GPA, wages went up by x%”, I would bet that someone “fit” the curve to simplify the chart and round-out different GPA scales and income variations around the country. Otherwise the method was deeply flawed. I would really like them to publish the raw data.

    Just because it’s on the internet doesn’t mean it’s true.

  3. river mt

    There is a correlation between intelligence and high school gpa. And correlation between educational attainment and high school gpa. And very high correlation with educational attainment, IQ and income. So i think the main driver is IQ and income. And educational attainment and income. And boys mature much slower than girls; that is why there is such a gender gap in high school gpa and income. Boys do become men and surpass women in math related fields which pay more money. Or they go straight into trades, which also pay good money. Also there is much more variance in males abilities which influence the income gpa gap. More men in lower ability and in higher abilities…

Please share your brilliant insights!