Using Regression to Adjust "Adjusted Points" for Top Tier Players '68-12
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02-24-2013, 12:03 PM
Czech Your Math
Join Date: Jan 2006
Originally Posted by
Sorry for my lack of understanding, but could you explain in a few words what the results of this study tells us?
There are numerous things that the results can tell us. I consider some of the most important things as follows:
A) Since expansion in '68, adjusted points have become progressively more difficult to score. As shown in the post with index numbers, the first decade after expansion it was rather easy to score adjusted points. From the time shortly before the WHA merger until the mid-90s, it was more difficult (but typically about average for the entire post-expansion period to date). Since the mid-90s (often referred to as the "dead puck era") it's been more difficult still to score adjusted points.
B) The reasons for the increasingly difficulty in scoring adjusted points appear to have been identified and quantified to a large degree. For instance, let's compare the three main eras as identified by the index numbers: the first decade after expansion ('68-'77), the typical non-expansion period surrounding the '80s ('78-'93), and the last two decades after the fall of the Berlin Wall ('94-'12).
The post-expansion period had an average predicted 1N (which is avg. adjusted scoring of top N players, where N is number of teams) of over 93. "The '80s" period had an average predicted 1N of over 88, a decrease of almost 5 points. The main reasons for the decrease were as follows:
- Parity increased significantly (variables Xf & Xa), which caused a drop of over 4 points.
- Expansion slowed significantly (variables Xh & Xi), which caused a drop of almost 1 point.
- The number of teams was larger (generally more difficult for larger group of players to maintain same average), which caused a drop of over 2 points.
- Power play opportunities increased substantially, which caused an increase of almost 2 points.
- The increased presence of non-Canadian players in the top 1N (variable Xe) caused an increase of over 1 point.
Those factors sum to a total decrease of almost 5 points (it may appear more like 4 points due to rounding errors). It was mainly expansion-related factors (new teams and lack of parity) which made it so much easier to score in the post-expansion period.
Now let's compare "the '80s" period to the "dead puck era". The predicted 1N actually increased from over 88 to over 89, almost a 1 point increase. Let's again look at the various factors:
- The larger number of teams caused a drop of 3 points.
- The increased presence of non-Canadian players in the top 1N caused an increase of 4 points.
- Other factors were rather minor, causing offsetting changes of about 1/2 point or less.
In this case the better talent pool including subsantially more non-Canadian stars obscured the fact that it became increasingly hard to score adjusted points.
C) Once the index numbers are more firmly established (I have to give more thought over time to whether/which other factors, besides presence of non-Canadians, should be factored out), then they can be used to calculate "adjusted adjusted" numbers, which we should have more confidence in using when comparing across seasons.
Last edited by Czech Your Math: 02-24-2013 at
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