Devin Pope writes:
I wanted to send you an updated version of Jonah Berger and my basketball paper that shows that teams that are losing at halftime win more often than expected.
This new version is much improved. It has 15x more data than the earlier version (thanks to blog readers) and analyzes both NBA and NCAA data.
Also, you will notice if you glance through the paper that it has benefited quite a bit from your earlier critiques. Our empirical approach is very similar to the suggestions that you made.
Here’s the key graph from the previous version:
And here’s the update:
Much better–they got rid of that wacky fifth-degree polynomial that made the lines diverge in the graph from the previous version of the paper.
What do we see from the new graphs?
– In the NBA, it’s no better to be ahead by a point than down by a point at halftime. In the NCAA, it appears to be better to be ahead.
– In either league, being ahead by one more point at halftime increases your change of winning by about 4 percentage points.
The abstract is clear:
Analysis of over 45,000 collegiate and 18,000 professional basketball games illustrates that being slightly behind at halftime leads to a discontinuous increase in winning percentage. Teams that are losing by a small amount win approximately 2 (NCAA) and 6 (NBA) percentage points more often than expected.
“More often than expected” is a good way to put it. Compared the previous draft, the estimate for the NCAA has declined from 6.6 percentage points to a more plausible 2 percentage points. The authors also do some supplementary analyses to rule out some other possible explanations.
It’s the online peer review system in action.
I just have one question: Why do the two graphs from the recent paper not include the data point at 0? This would supply some information, no?