MASH Report (2/4/16) – Bookmark Edition
• In my December 10th MASH article, I ran Rob Arthur’s projected days missed for hitters. Commentor jfee noted:
the total batter injury days projects out unrealistically low.
Projected days lost to injury – 2700
Days lost last year – 7643
Days lost prev year – 6015
Days lost year 3 – 5391I can understand why player turnover would lead to the difference in actual injury from last year to yr3. But projecting that these same players will, next year, become so so healthy seems to involve PED’s (or perhaps a baseline injury rate – regression intercept – that hasn’t been included)
I finally found some time to look into the question and he was right. Using just linear regression and the inputs to the equation, I came up with the formula which set a min of 10 days missed per player:
Total DL days = 4.8 + .26 * age + 0.1 * DL Days in Year -1 + 0.03 * DL Days in Year -2 + 0.02 * DL Days in Year -3
Besides the age and constant, the other three numbers were close to Rob’s numbers:
Days missed this year = .18*(days missed last year) + .1*(days missed two years prior) + .02*(days missed three years prior) + .004*Player’s Age
