[beineke]

Player age on Dec 31 (end of year), weighted by the number of minutes played.

1996 -- 28.49
1997 -- 28.67
1998 -- 28.75
1999 -- 28.66
2000 -- 28.73
2001 -- 28.62
2002 -- 28.24
2003 -- 27.92

The age was essentially constant for the first six years of the league. Only in the past two years has the age begun to drop. I think this is evidence that programs like Project-40 and Bradenton are starting to pay dividends.

It's also interesting to note that the drop in age occurred after contraction, while the expansion year was the oldest. Perhaps these numbers are skewed by the presence of aging imported players. At some point, I'll re-run them omitting foreigners and see what happens.

[beineke]

Ok, I ran the numbers for US-eligible players only...
1996 -- 28.01
1997 -- 28.11
1998 -- 28.00
1999 -- 27.90
2000 -- 28.01
2001 -- 28.00
2002 -- 27.77
2003 -- 27.61

The pattern looks pretty similar. Expansion in 1998 might have opened a few doors to younger players in 98 and 99, but contraction in 2002 doesn't seem to have frozen out the younger players.

[sljohn]

You wouldn't happen to have a standard deviation for each one of those means, would you?

I'd be curious to know if there is a statistically significant difference between 2003 and other years.

[beineke]

Originally posted by sljohn
You wouldn't happen to have a standard deviation for each one of those means, would you?

I'd be curious to know if there is a statistically significant difference between 2003 and other years.

[Using the data for US-eligible players]

If we assume that all variation in years 1-6 is random, then the estimated s.d. is 0.067 and the mean is 28.01. (Note that any real change would inflate this estimate, hence reducing the significance of future changes.)

The drop from years 6 to 7 is by 3.6 standard deviations, and the drop from years 7 to 8 is by an additional 2.4 standard deviations.

Conclusion: highly significant


Fair question, but that's actually non-trivial to compute ... if you want to compare 2002 to 2003, you have to adjust both years for Preki simultaneously.

[kenntomasch]

Does it make a big difference if you use July 1 rather than December 31?

I'm working on some studies with age as well, and wondering if the age at the midpoint of the year makes a difference or not.

I guess if someone's birthday is July 7, they're not significantly different on June 30 than on July 14, but the number would be different.

Just curious. Probably doesn't matter.

[beineke]

Originally posted by kenntomasch
Does it make a big difference if you use July 1 rather than December 31?

I'm pretty sure it doesn't make a difference, but the only data I have is year of birth, so I don't have any way to confirm.

[mpruitt]

Thanks for crunching those numbers. Im suprised that the numbers have remained so relatively constant. I'm not suprised that the number was down rather signifigantly this year. It'd be interesting to run some numbers too if you gave a min. minutes played floor. It'd be challenging to figure out the average age of 'starters.' But maybe at a predetermined # of games of # of minutes would yeild some interesting stuff.

[kenntomasch]

Don't know how much use this information is, but if you graph simply the age of each of the 230 players who played minutes in MLS this season (age as of July 1), you get a bell curve with the high point at 26:


16...1
17...2
18...4
19...2
20...7
21..17
22..27
23..21
24..19
25..24
26..31
27..13
28..11
29..10
30...7
31...7
32...9
33...7
34...5
35...3
36...1
37...1
38...0
39...0
40...1


That's obviously unweighted towards minutes played, which is a good way that Phil does it. This is strictly showing the number of players in MLS of a particular age. There were 16 players under 21, and only 18 older than 32.

BTW, Phil, when I weighted the average age towards minutes played (and I hope I did it the same way you did), I got 26.52 using July 1, which makes sense because the other 6 months basically gives you another "year" on (probably about) half of the players. But I would imagine the relationship between all the years, if you did the average age by using July 1, would show the same pattern as it does using December 31.

And I have everyone's birthdate now, if you want that data (if it would help you at all).

[beineke]

Originally posted by maxim-1
Thanks for crunching those numbers. Im suprised that the numbers have remained so relatively constant.

Me too, though I think the average might be masking some interesting effects. My belief (which needs to be verified) is that while the average was staying constant, the US player pool was simultaneously getting both older and younger.

At the outset, the great majority of US players in MLS were in the age range from 24 (McBride, Armas) to 31 (Doyle, Trittschuh). As this generation got older, we had a gradual increase in the numbers of over-30 players. At the same time, the league also began to add players like Corrales, Olsen, Wolff, etc., who were able to start contributing as college-aged players. Perhaps the story isn't a shift in the average, but rather a widening of the age range?

[Kenn -- it doesn't look to me as if our numbers are in agreement. I'll try to go back soon and double-check what I've done.]

[mpruitt]

Originally posted by beineke
Me too, though I think the average might be masking some interesting effects. My belief (which needs to be verified) is that while the average was staying constant, the US player pool was simultaneously getting both older and younger.

At the outset, the great majority of US players in MLS were in the age range from 24 (McBride, Armas) to 31 (Doyle, Trittschuh). As this generation got older, we had a gradual increase in the numbers of over-30 players. At the same time, the league also began to add players like Corrales, Olsen, Wolff, etc., who were able to start contributing as college-aged players. Perhaps the story isn't a shift in the average, but rather a widening of the age range?

[Kenn -- it doesn't look to me as if our numbers are in agreement. I'll try to go back soon and double-check what I've done.]

Yeah we may be missing something in terms of turnover of players. You may have hit it in terms of core guys who came into the league young and are still here. Kenn's style analysis would be interesting to see for year per year. Either way I think that the decrease of this year is signifigant and is an example of the MLS 'youth movement.'