Matt Johnson, a grad student in biology, (respectfully) takes my English-majoring, med-school-attending behind to school in a fantastic post at his blog The Immaculate Inning.
Without saying that my statistical analysis is rudimentary, Johnson simply blows it out of the water.
Basically, he does what I did, compare efficiency margin to Duke's progress through the ACC season. Except where I grossly oversimplified and ignored possible confounders, he applied statistics, correcting Duke's overall downward trend for quality of opponents and home/away factor.
In the end, he makes several great points:
- Duke's opponents improve as the season go on. Part of this is the Carolina Effect -- Duke plays the Tar Heels twice in the latter half of the schedule, and they're almost always (not this year!) the best ACC opponent on the schedule -- part of this is a result of playing two quality opponents in the ACC Tournament most years, and part of this could stem from the ACC's TV partners' desire to put appealing matchups later in the year.
- Duke plays better against lesser opponents. This seems obvious, but Johnson has a scatterplot with a trendline to prove it.
- This increase in opponent quality as the season goes on partly (but doesn't entirely explain) Duke's tendency to fade through the course of the ACC season.
- He also takes me to task for glossing over (and/or ignoring) the fact that two seasons (2008 and 2004, a Final Four year) actually had declines that rose to the level of statistical significance.
As he summarizes:
I must say I come away unimpressed with other explanations for the Duke Fade. Opponents do get tougher but not enough to overcome the efficiency drop. Adjusting for home and away games also doesn't have much of an effect. It is very important to note that nowhere have I suggested a causal agent for the Duke Fade. This is to avoid the common fallacy that correlation implies causation. Clearly, Duke can still have an historic season (2004) despite having one of the few significant in-year Duke Fades.
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