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NFL players: height and weight over time

noahveltman.com

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Re: NFL players: height and weight over time

#121

Post by derekjobst »

maxerickson wrote: post #43
derekjobst wrote: post #22

What's interesting is before the 1970's it appears as though there is just one group of players, at which point they become three. Then, over the following 40 years these groups seems to just get heavier - most likely a response by teams to maintain heavier players than their opponents in certain positions. While the general growth over time makes sense, I wonder what caused the shift specifically in the 70's.

Everybody is saying steroids, but another thing that happened around the 1970-80s is that college football became a much bigger business: http://en.wikipedia.org/wiki/College_football_on_television#...

Oh, that is very interesting.

Re: NFL players: height and weight over time

#123

Post by CognitiveLens »

ronaldx wrote: post #70
mbauman wrote: post #15

Earlier quoted context omitted.

Ugh, on [3], watch out for the non-zero axes. NHL and NBA start their axes at 0, while the others do not. Very tricky, and very deceiving. I think NFL would look very similar to NBA if plotted the same way (they're both within ~10-15% of the expected value).

The author points out in the text that the NFL result is statistically significant and the NBA result is not. A larger random sample ought to fall closer to the line than a smaller sample: it would be statistically highly remarkable if the graphs did look similar with zeroed axes - the larger sample should look much flatter. Starting both graphs from zero is unhelpful if the goal is correct visual interpretation.

With broad correlational data like this, it's important to know what significance threshold is being used, and what the significance value actually is. There are many possible analyses that can be run, and there will be some subset of those analyses that produce significant results by chance, which is why you need hypothesis-driven analysis and/or very conservative corrections for post-hoc analysis.

Without the details, we can't evaluate significance claims.

Re: NFL players: height and weight over time

#124

Post by dobbsbob »

at-fates-hands wrote: post #72
silverbax88 wrote: post #46

Earlier quoted context omitted.

When I was in high school I was a Division I football prospect. I had multiple schools after me: Alabama, Florida, LSU, etc. I really wanted Miami (this was the '80s) but deep down I really wanted to play basketball. I only got a little sniff of DI basketball interest but I went on a football visit to Florida and saw massive guys hitting each other and thought "I'm going to get killed" and never took the football sch…

You sound remarkably similar to what Wayne Gretzky said after he retired. The last two years of his career, his Dad kept asking him if he was going to play another year. He basically said, "I don't know. Every year I go back to camp, the guys are bigger, stronger and hit harder than last year." When you look around the league, it's obvious how much bigger these guys have gotten. Look at some of the current LA KINGS f…

In hockey there's a strategy for this you both grab each other and slide in at the same time to avoid getting killed on the boards. When Gretzky played no other player could hit him because they didn't have the instigator rule, so if you clobbered him on the boards the biggest goons on his team would take your head off so the result was nobody touched Gretzky until late in his career when they put in that stupid rule.

Hockey also has the problem of players wearing body armor now so hits are even worse than what they used to be.

Re: NFL players: height and weight over time

#125

Post by mhb »

Zelphyr wrote: post #40
skierscott wrote: post #25

Earlier quoted context omitted.

Malcolm Gladwell has looked at this issue[1]. He sees football as being analogous to dogfighting. Popular at the time and with fans, but the science behind it is scary. I've experienced a severe traumatic brain injury (sTBI), meaning I've seen many brain doctors. I have seen a neuro-omptomolgist (brain-eye doctor) who sees a football player who can't even add up his checkbook (meaning he can't add, not this his check…

> I'll never let my children play football. I wish more people had this attitude.

Football’s Risks Sink In, Even in Heart of Texas

http://www.nytimes.com/2014/05/12/sports/footballs-risks-sin...

Re: NFL players: height and weight over time

#126

Post by craigmbooth »

ronaldx wrote: post #104
sesqu wrote: post #100

Earlier quoted context omitted.

One could argue that the large difference in sample sizes (more than fivefold) justifies scale manipulation to bring the variances into line, but it doesn't appear to me that the author normalized on variance at all (the axis should be something like 800-2000).

I agree with what you say. To correctly compare the variances, the scale should be adjusted according to the square root of the ratio of sample sizes. The author has not done this correctly, but I claim that zeroing the axis would be further from the correct graph.

Ah, you are correct, thank you. Apparently I wasn't thinking clearly when I normalized the axes to have the same absolute ranges.

Re: NFL players: height and weight over time

#127

Post by craigmbooth »

drpgq wrote: post #78
incision wrote: post #6

Craig M. Booth has done some very nice visualizations on this subject [1]. I found this chart comparing height/weight of 2013 rosters by position [2] particularly interesting and this set [3] covers a question that anyone who has read Outliers has probably wondered about. 1: http://www.craigmbooth.com/category/nfl/ 2: http://www.craigmbooth.com/height-and-weight-of-every-active... 3: http://www.sportsballweekly.com/t…

For number 3 and NBA players, wouldn't the fact that having to be so tall would trump the age effect? Being 7 feet tall is an extremely rare statistic event, so whether the player is born in January or December isn't material.

Heh. This is far better than the explanation I could think of. Thanks.

Re: NFL players: height and weight over time

#129

Post by jessriedel »

markdown wrote: post #96
jessriedel wrote: post #90

Earlier quoted context omitted.

My understanding is that the concussions in soccer come from direct head-to-head collisions (which are not cushioned by helmets) and from heading the ball (which is moving significantly faster than a human being). The fact that you find the similar concussion rates between these two sports surprising is good reason for you to doubt your ability to identify dangerous sports based on your intuition for how violent they…

Head to head collisions are relatively rare. You could play an entire career without getting one. Heading the ball isn't that bad, actually, and certainly doesn't happen often. Players can go through a season without ever doing it. Either you don't watch much Football, or you don't watch much American Football. One only needs to watch a few games of each to see how violent they are. American Football has dozens of pe…

You're right. I better watch more TV so I don't have to pay attention to that pesky data any more.

Re: NFL players: height and weight over time

#130

Post by kasey_junk »

learc83 wrote: post #113
jessriedel wrote: post #68

Earlier quoted context omitted.

Nice anecdotes. Your comments and links are good at triggering fear, but the data doesn't back you up that football is an usually dangerous sport. Women's soccer has a higher rate of concussions than men's football at the collegiate level, and it has 75% of the rate at the high school level [1]. Similarly, men's college soccer has a higher rate than high school football. In fact, football is higher than the average s…

The thing you're missing is Chronic traumatic encephalopathy. The current theory is that CTE can be caused by the constant repeated non-concussive hits unique to football (at least among popular American sports), so analyzing concussion rate really isn't helpful. >A brain injury study conducted at the Boston University School of Medicine showed that 33 of 34 players tested post-mortem showed clear signs of CTE.[1] Ev…

There is a lot of evidence mounting that CTE is a problem in soccer as well. Not from head to head collisions but as a sort of repetitive stress injury from heading the ball. Teams are starting to put players, especially at the youth level, on header counts during practice to mitigate this.

As I see it there are a variety of ways to become injured in sports: - traumatic injury such as concussion, spinal injury, torn ligaments, broken bones, etc. - repetitive stress injuries such as CTE, tendinitis, stress fractures, etc. - what I'll call body stress injuries. Things like putting on too much weight for your frame to play lineman in football, extreme weight dropping for weight class sports, or the extreme oddities professional cyclists put themselves through for an advantage.

Nearly every sport you play has some chance of having injuries in at least one of these categories. The problem is that football has a high likely hood of injuries in all of these categories, and at the worst case of the injury in the category.

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