Ravens OL John Urschel, 26, retires abruptly, two days after CTE study

Re:Ravens OL John Urschel, 26, retires abruptly, two days af... by camiller on Thursday July 27, 2017 @03:17PM (#14868459)

Unfortunately n, in this paper, doesn't seem to mean sample size like you would expect in statistics. It is an extrapolated number of concussions nationwide based on a study of 100 high schools.

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Re:Ravens OL John Urschel, 26, retires abruptly, two days af... by kelnos on Thursday July 27, 2017 @04:03PM (#14868917)

That still doesn't mean you can just add the percentages. You cannot determine the percent of boys+girls soccer head injuries without knowing the sample sizes.

Or, if you can figure out the relative difference between the number of boys and girls who play soccer, you can do a weighted average of the percentages.

Either way, adding the percentages is completely incorrect.

EDIT: http://www.usyouthsoccer.org/media_kit/keystatistics/ suggests that the split is roughly equal -- in 2008 it was 52% boys and 48% girls.

With that said, the correct weighted value is more like 21.5x.48 + 15.4x.52 = 18.3%, which is significantly less than the 40.5% you quoted for football.

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Re:Ravens OL John Urschel, 26, retires abruptly, two days af... by camiller on Thursday July 27, 2017 @04:41PM (#14869264)

per the source material there were a total (extrapolated) of 135901 concussions across the 9 sports studied.

55007 for football - 40.5% of 135901

20929 for boys soccer - 15.4% of 135901

29167 for girls soccer - 21.5% of 135901

50096 combined soccer

50096/135901 = 36.9% of all concussions were from soccer.

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Re:Ravens OL John Urschel, 26, retires abruptly, two days af... by jotux on Thursday July 27, 2017 @06:24PM (#14870209)

You are correct. That is such an odd way to represent data like this.

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