Sunday, September 27, 2009

Does throwing a hook increase the likelihood of a strike?

Happy anniversary! This is the 100th all time post on the BM Report. When I started this blog, I didn't know if it would have legs, but it seems to, even if they are short and stumpy. I thought I'd try to answer a classic bowling question for this one. So, the question of the day is whether throwing a hook shot, a curve, or a spin increases your chances of getting a strike. Everybody who throws a hook believes the answer is yes, and that has certainly been our personal experience.

The best way to answer this question would be controlled experimentation, and I'm fairly certain that this has been done. Anyway, here is how I approached the question. First, for the last two years, three of us (JD, JL, and myself) have been throwing a hook. The 4th bowler, whether it has been the Canadian or Gingy have thrown a classic straight ball. So, first we can ask who gets more strikes? The "hookers" or the straight men? Unfortunately, that analysis is confounded by another variable, namely skill. Those of us who throw a hook have considerably more experience than the straighty's which could explain any observed differences, so fundamentally what I want to ask is when a ball hits the pocket, who gets more strikes?

In this vein, in the 2nd analysis, I looked only at frames with first ball scores of 9 or X. I assume that if a bowler got a 9 or an X then the ball was in the pocket. I know this isn't always true, but most of the time it is. So if you look at the total number of frames in which 9's and X's occur and examine the relative frequency of each, it should tell you who is more likely to get a strike when the ball hits the pocket, straight on bowlers, hookers, or perhaps there is no difference between the two. So here we go...

The graph above shows strike percentages for five bowlers, three who throw hooks, and two straight ballers. This graph tells us very little except that we all suck at getting strikes. Yes, those of use who throw hooks have a greater likelihood of getting a strike on any given frame than the straight on guys, but that does not mean a whole lot. It probably means that we have been bowling longer. In sum, hookers have strike percentage of 28% and straighty's come in at 17%. We could pick up a hell of a lot more strikes than we do. I would be happy to see those numbers get up around 40%.

Ok, but what if we only look at likely pocket shots, those frames that ended up with a first ball score of 9 or X? Again, a similar pattern is evident with one exception, the Ging man. When we have a likely pocket shot (a 9 or X), John, Joe and I have strike percentages between 53 and 59%. Gee-off, last year's straight bowler, has a strike percentage of only 41%. Gingasaurus Rex unfortunately ruins this pattern. His straight ball has been very effective at picking up strikes when his house ball is in the pocket (55.6%). My hunch is that the Ging anomaly is due to sample size. We only have 36 frames recorded for JG in which a strike or 9 occurred in comparison to hundreds of frames for everybody else. Parenthetically, his strike percentage is statistically indistinguishable to those for both hook and straight ball throwers. This means with a larger sample size, he could stay right where he is, or drop down with the Canadian. My gut tells me that it will be the latter.

If we combine the data for all straighty's and hookers (shown below), the pattern is very evident. For the three of us who throw a hook, if the ball is in the pocket, there is a 55% chance that we will get a strike. For straight ballers, it's only a 43% chance, and this difference is highly significant.

I suppose one could question whether these results are universal, meaning whether they would apply to all bowlers, particularly very high skill bowlers. To be honest, I don't know. At least for our team, it looks like throwing a hook gives you approximately a 12% advantage at knocking down all ten if you find the pocket.

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