Do Southpaws Get a Fair Shake in MLB?

There have been a few blog posts recently on a new NBER article Handedness and Earnings (Everyday Economics, Marginal Revolution, and Greg Mankiw). The general results are reported in The Washington Post.

“Among the college-educated men in our sample, those who report being left-handed earn 13 percent more than those who report being right-handed,” said economist Christopher S. Ruebeck of Lafayette College. Ruebeck and his research partners, Joseph E. Harrington Jr. and Robert Moffitt of Johns Hopkins University, reported the findings in a new working paper published by the National Bureau of Economic Research.

However, it’s interesting that there is no concrete theory as to why this gap exists, and why it occurs in men but not women.

While evidence of a wage gap was unequivocal, explanations for the disparity proved more elusive. Differences in biology and brain function are two possibilities. Nor do the researchers know why they didn’t see a similar effect among women.

Tyler Cowen hypothesizes that there is something special about being left-handed, which I think fits with the conventional wisdom.

Left-handers have idiosyncrasies, obsessions, and downright insanities which lift some of them into productivity heaven.

But I’m curious. Left-handedness is not something traditionally viewed positively by society. The Latin term for left is sinister. Are modern day lefties overcoming a past bias and now surpassing righties?

Anyway, I wanted to see how left-handedness plays out in baseball. Because handedness plays a role in the success of players—because of the platoon effect— I had to be careful to control for other characteristics.

So, I went to the trusty Lahman Baseball Database and looked at all batters from 1985-2005. I estimated the impact of hitting performance, age, and handedness on yearly earnings of free agent eligible players using multiple linear regression. Also, I used a sample of only pure left-handed and right-handed players, taking out all switch hitters and players who throw and bat with opposite hands. Here is what I found.

Left-handers earn about $225,000 less than right-handers, but the difference is not statistically significant, meaning the estimate is within the expected variation. However, that’s nearly 6% less than the average player in this sample, which is nothing to sneeze at. But, more importantly, there does not seem to be evidence of lefties earning more than righties among hitters. This certainly isn’t perfect, and I can think of a few problems. The main weakness is that lefties are barred from playing four defensive positions: catcher, third, shortstop, and second. Because I’m using only offensive stats, equally good-hitting lefties may not be as valuable as righties. I’ll post the results below if you’re interested. I’m not sure what it means about why left-handers earn more in the general workforce, but this doesn’t seem to hold for baseball hitters. Maybe I’ll do pitchers next.

Variable	Coefficient	T-stat
AVG		$10,800,000	4.21
Walk Rate	$13,300,000	6.17
Iso-Power	$11,600,000	9.07
Left-Handed	-$225,676	-1.35
Age		-$297,196	-0.81
Age2		$4,337		0.79
R2		.51 
(year effects and constant not reported)

Addendum: See Part 2 for analysis of pitchers.

One Response “Do Southpaws Get a Fair Shake in MLB?”

  1. J. Cross says:

    Are left-handed power hitters overrated by PrOPS? I wonder if PrOPS might be a good way to measure the effectiveness of “the shift” that’s put in place against many/most of these hitters.