12 August, 2015

2015 Win Prediction Totals (Through July)

These are a bit late - it's August 12, but these intervals only include games through July 31.

These predictions are based on my own method (which can be improved). I set the nominal coverage at 95% (meaning the way I calculated it the intervals should get it right 95% of the time), and I think by this point in the season the actual coverage should be close to that.

Intervals are inclusive. All win totals assume a 162 game schedule.

\begin{array} {c c c c}
\textrm{Team}  & \textrm{Lower}  & \textrm{Mean} & \textrm{Upper} & \textrm{True Win Total} \\ \hline

ATL & 64 & 72.27 & 81 & 72.09 \\
ARI & 73 & 81.38 & 90 & 83.36 \\
BAL & 74 & 82.90 & 92 & 86.17 \\
BOS & 64 & 72.12 & 81 & 72.94 \\
CHC & 76 & 85.07 & 94 & 81.23 \\
CHW & 68 & 76.53 & 85 & 73.10 \\
CIN & 66 & 74.63 & 84 & 76.06 \\
CLE & 68 & 76.90 & 86 & 78.07 \\
COL & 62 & 70.37 & 79 & 72.69 \\
DET & 70 & 78.54 & 87 & 78.37 \\
HOU & 82 & 90.46 & 99 & 90.71 \\
KCR & 85 & 94.02 & 103 & 89.14 \\
LAA & 78 & 87.28 & 96 & 87.11 \\
LAD & 82 & 90.37 & 99 & 88.88 \\
MIA & 61 & 70.09 & 79 & 77.17 \\
MIL & 63 & 71.01 & 80 & 75.43 \\
MIN & 74 & 82.43 & 91 & 79.51 \\
NYM & 74 & 82.33 & 91 & 80.50 \\
NYY & 82 & 90.45 & 99 & 87.62 \\
OAK & 67 & 75.23 & 84 & 84.46 \\
PHI & 54 & 62.61 & 71 & 63.10 \\
PIT & 83 & 92.27 & 101 & 87.16 \\
SDP & 69 & 77.14 & 86 & 74.48 \\
SEA & 65 & 73.45 & 82 & 73.91 \\
SFG & 79 & 88.31 & 97 & 87.21 \\
STL & 92 & 101.20 & 110 & 96.66 \\
TBR & 72 & 80.88 & 90 & 80.62 \\
TEX & 70 & 78.37 & 87 & 76.62 \\
TOR & 77 & 86.00 & 94 & 92.18 \\
WSN & 77 & 85.99 & 95 & 84.89 \\ \hline\end{array}
To explain the difference between "Mean" and "True Win Total"  - imagine flipping a fair coin 10 times. The number of heads you expect is 5 - this is what I have called "True Win Total," representing my best guess at the true ability of the team over 162 games. However, if you pause halfway through and note that in the first 5 flips there were 4 heads, the predicted total number of heads becomes $4 + 0.5(5) = 6.5$ - this is what I have called "Mean", representing the expected number of wins based on true ability over the remaining schedule added to the current number of wins (at the end of July).

As a bonus, these quantiles are based off of a distribution - I've uploaded a picture of each team's distribution to imgur. The bars in red are the win total values covered by the 95% interval. The blue line represents my estimate of the team's "True Win Total" based on its performance - so if the blue line is lower than the peak, the team is predicted to finish lucky, and if the blue line is higher than the peak, the team is predicted to finish unlucky.