Men’s and women’s volleyball has different characteristics. Everyone knows that. But exactly how different? I’m glad you asked. I scrounged up the complete dataset of matches of the 2019 men’s and women’s FIVB Volleyball Nations League** and put them in the Science Untangled reporting app. This is what I discovered. In this post I look at the simple correlations of different areas with set win percentage. A word of caution, I don’t know much about actual statistical analysis, but I know enough to know that this is very superficial. I figure it is enough to at least create some topics of conversation and gently challenge some conventional wisdom. Part 1 is here.
Sideout Phase – Sideout percentage correlates best overall to set win percentage in both men’s and women’s VNL. Interestingly, modified sideout percentage (i.e. excluding service errors) is less highly correlated. First Ball Sideout (FBSO, i.e. scoring on the first ball) is important for men, but only moderately important for women. Women need to be good at wining the extended rally in the sideout phase. Reception, measured by expected SO%, is not highly correlated and even less correlated for women. This seems strange on the surface, most people think of reception as being very important. This suggests that maybe it is not as important as conventional wisdom holds.
Breakpoint Phase – Breakpoint percentage is highly correlated to success but less highly than is sideout percentage, again more highly for men than women. Excluding service errors also lowers the correlation. Stopping the opponent scoring on the first sideout attempt is pretty important for men, but not really important for women. Serving, measured by expected BP% (using the same principle as SO%) is a little bit important for men, but not at all important for women. The old adage ‘Volleyball is serve and pass’ doesn’t seem to be supported by this simple analysis. When correlated with SO% and BP%, reception and serve (not shown in the charts) do come up as a bit more important (~0.60) than when correlated with winning.
Skills – Attack is very important in volleyball. Scoring points (as distinct from avoiding errors) is very important in volleyball. More important indeed than anything else, and both are more important in women’s volleyball. I could not look at errors due to the different scouting conventions being used (see ** below). Aces are completely irrelevant for men and more or less irrelevant for women. Block percentage is mildly interesting. Most shockingly of all, defence (as measured by attacks per defensive opportunity) is much, much less important for women than for men. I must admit that surprises me a lot, at least on the basis of general perception of the men’s and women’s volleyball. Some food for thought.
So there you have it. The final word ( 😉 ) on the differences between men’s and women’s volleyball. At a later date I hope to do a profile of rally lengths. On that topic, for the time being all I can say is that in men’s volleyball 71% of rallies finish without the serving team having opportunity to attack, versus 58% for women. Further the average number of net crosses per rally is 1.52 for men and 1.83 for women.
**For the record, the files (251 matches in total) come from different sources and have not been individually controlled. There may be a variety of different scouting conventions used, not least between men’s and women’s teams. However, for the purposes of this overview (ie informal comparison) we can assume the basic measures are valid. Except for errors. Many (but not all) women’s scouts seem to use B= and B/ differently to men’s scouts.
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