S.A.D. Predictions - Eights 2015

Iteration#3: 28th May

First SAD BaStaRD iteration, modifying original estimates provided by: AB, RC, AD, SH, CW, JW with results of Wednesday's racing.

Predictions for the Saturday finishing order using the Statistical Analysis of Divisions (SAD) program based on collective estimates of boat speeds (top divisions only).

The following tables show the WEDNESDAY starting positions of each crew, its score and average predicted change in position by the end of the week, followed by the crews most likely to occupy that position at the end of the week, listed in order of decreasing probability.

Click on crew name for graphics showing evolution of SAD score with each iteration and spread of Predicted Net Changes over the week.

The Evolution of SAD Score shows score each iteration as a red cross, the vertical extent representing the uncertainty. The previous Torpids score used as an initial estimate and its associate uncertainty is shown as a green box. The Norm for the crew's starting position is shown as a blue dashed line. In the absence of any new information, each iteration the score will relax towards the "Norm" and the error bar expand towards ±1. If new estimates have been supplied the error bar will get smaller. This plot is updated as new scores come in, ie prior to the next formal iteration when the full SAD prediction is rerun. These intermediate scores are located half way between the last and the next iteration on the horizontal axis.

The Predicted Net Change histogram plot shows the probability of different net gains in position over the week (blue columns for rises, red columns for falls, white for remaining the same). The dashed line shows the mean change in position averaged over all possible outcomes (all the information for these histograms is extracted from the tables below).


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Men's Divisions 1-3

Pos Start Crew Score Av.Rise Finishing Crew
1Oriel 6.7 -0.1 Orie 94% Chri 6% Pemb 0% Magd 0%
2Pembroke 6.0 -2.1 Chri 92% Orie 6% Pemb 2% Magd 0%
3Christ Church 6.6 +1.0 Magd 71% Pemb 26% Chri 2% Wolf 1% Orie 0% Trin 0%
4Magdalen 6.4 +0.7 Pemb 36% Wolf 36% Magd 26% Trin 1% Chri 0% Univ 0% Ball 0%
5Trinity 5.8 -1.2 Wolf 49% Pemb 35% Trin 12% Magd 2% Univ 2% Ball 0%
6University 5.8 -1.3 Trin 57% Kebl 19% Wolf 12% Univ 9% Ball 2% Pemb 1% Magd 0%
7Wolfson 6.4 +2.2 Univ 47% Trin 25% Kebl 22% Ball 5% Wolf 2% SCat 0%
8Balliol 5.6 -0.8 Univ 39% Kebl 29% Ball 25% Trin 5% SCat 1% Wolf 0% SEdm 0% NewC 0%
9St Catherine's 5.2 -2.6 Ball 51% Kebl 25% SEdm 9% Wadh 6% SCat 5% Univ 3% Trin 1% NewC 0%
10Keble 6.1 +2.2 SEdm 36% Wadh 27% SCat 15% NewC 10% Ball 9% Kebl 3% Worc 0% Univ 0%
11Worcester 5.0 -3.0 Wadh 38% SEdm 24% SCat 22% NewC 8% Ball 7% Kebl 1% Worc 1% Hert 0%
12St Edmund Hall 5.6 +1.0 NewC 34% SCat 25% Wadh 22% SEdm 16% Worc 2% Ball 0% Kebl 0% Hert 0%
13Wadham 5.9 +2.0 NewC 40% SCat 32% Worc 11% SEdm 10% Wadh 7% Hert 1% Linc 1% Kebl 0%
1Hertford 4.8 -1.9 Worc 70% Linc 13% NewC 7% SEdm 5% Hert 4% Wadh 1% Bras 0%
2New College 5.9 +2.7 Linc 40% Hert 36% Worc 17% Bras 5% NewC 2% SEdm 0% SJoh 0%
3Lincoln 5.1 +0.4 Hert 34% Bras 34% Linc 31% NewC 0% SJoh 0% Lady 0% SAnn 0% Mans 0%
4St John's 4.2 -3.0 Mans 67% Bras 17% Hert 9% Linc 4% Lady 1% SAnn 0% Jesu 0% SJoh 0%
5Brasenose 5.0 +1.0 Bras 40% Mans 29% Hert 16% Linc 10% SJoh 2% Lady 1% SAnn 1% NewC 0%
6L.M.H. 4.6 -1.8 Jesu 69% Lady 16% SJoh 7% Mans 3% SPet 3% SAnn 2% Bras 1% Linc 0%
7St Anne's 4.4 -2.9 SJoh 74% Jesu 21% Bras 2% Lady 1% SPet 1% SAnn 1% Ori2 0% Mans 0%
8Mansfield 5.6 +3.6 Lady 55% SJoh 17% Ori2 13% Jesu 7% SPet 4% SAnn 4% Mans 0% Bras 0%
9St Peter's 4.3 -2.3 Pem2 26% Lady 23% Ori2 21% SAnn 19% SPet 8% Jesu 3% Exet 0% Mans 0%
10Jesus 5.6 +3.5 SAnn 40% Pem2 39% Ori2 13% SPet 6% Lady 2% Jesu 1% Exet 1% ChC2 0%
11Oriel II 4.8 +0.6 SAnn 33% SPet 23% Ori2 22% Pem2 18% Exet 2% Jesu 1% ChC2 1% Some 0%
12Exeter 4.1 -2.0 SPet 31% Ori2 25% Pem2 13% Quee 13% Exet 8% ChC2 6% Some 2% Corp 0%
13Pembroke II 5.2 +2.7 Quee 32% SPet 24% Exet 18% ChC2 14% Ori2 5% Some 4% Pem2 2% Corp 1%
1Christ Church II 4.2 -0.5 Exet 37% Quee 28% ChC2 26% Some 5% Corp 4% Pem2 1% Ori2 1% SHug 0%
2Corpus Christi 3.8 -1.8 ChC2 34% Exet 27% Quee 21% Corp 7% SHug 4% Some 4% Mert 3% Pem2 0%
3Somerville 3.8 -1.6 Corp 25% SHug 21% ChC2 14% Some 14% Mert 12% Exet 9% Quee 6% Pem2 0%
4Queen's 4.7 +3.2 Corp 34% SHug 25% Mert 23% Some 11% ChC2 5% Quee 1% Mag2 1% New2 0%
5St Hugh's 4.1 +0.3 Mert 26% Lina 21% Corp 20% SHug 17% Some 12% New2 1% ChC2 1% Mag2 1%
6Merton 4.2 +0.9 Lina 28% Some 24% SHug 15% Mert 15% Corp 9% New2 5% Mag2 2% Uni2 0%
7New College II 3.6 -1.4 Lina 24% Some 22% Mert 19% SHug 15% New2 15% Mag2 4% Corp 0% Wad2 0%
8Magdalen II 3.1 -2.0 Uni2 73% New2 15% Lina 6% Mag2 4% Mert 1% SHug 1% SEH2 0% Wad2 0%
9Linacre 4.3 +2.1 New2 55% Uni2 24% Lina 13% Mag2 6% Mert 1% SEH2 1% SHug 0% Wad2 0%
10Wadham II 2.9 -2.1 Mag2 45% SEH2 15% Wad2 11% Bal2 10% New2 7% Lina 7% Uni2 3% Keb2 1%
11St Edmund Hall II 3.3 -1.1 Mag2 33% SEH2 28% Wad2 20% Bal2 16% SAnt 1% Keb2 1% Lina 1% New2 1%
12University II 4.6 +3.7 Keb2 47% Wad2 21% Bal2 14% SEH2 10% Mag2 4% SAnt 4% Lina 0% Tri2 0%
13Exeter II 2.4 -2.7 Wad2 42% Keb2 25% SEH2 21% Bal2 7% SAnt 4% Mag2 0% Tri2 0% Lina 0%
1Trinity II 2.5 -2.9 Bal2 38% SEH2 24% Keb2 12% SAnt 9% Exe2 6% Tri2 5% Wad2 5% Mag2 0%

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Women's Divisions 1-3

Pos Start Crew Score Av.Rise Finishing Crew
1Wadham 6.6 -0.4 Wadh 75% SJoh 18% Pemb 7% Magd 0%
2St John's 6.4 -0.4 SJoh 44% Pemb 34% Wadh 17% Magd 4% SEdm 0% Chri 0%
3St Edmund Hall 5.5 -3.5 Pemb 43% Magd 31% SJoh 21% Wadh 5% SEdm 0% Chri 0%
4Pembroke 6.5 +1.3 Magd 60% Pemb 13% SJoh 12% Univ 11% Wadh 2% Chri 1% SEdm 1%
5Magdalen 6.5 +1.4 Univ 69% Chri 14% SJoh 6% SEdm 4% Magd 4% Pemb 2% Ball 1% Wadh 1%
6Christ Church 5.8 -1.5 SEdm 37% Wolf 19% Univ 17% Kebl 14% Chri 11% Pemb 1% Ball 1% Magd 0%
7Balliol 5.7 -2.6 SEdm 58% Wolf 13% Chri 13% Kebl 11% Ball 2% Univ 2% Pemb 0% Magd 0%
8University 6.5 +2.9 Chri 35% Wolf 34% Kebl 22% Ball 7% Orie 1% Univ 0% Pemb 0% Magd 0%
9Keble 6.1 +0.5 Wolf 28% Ball 26% Chri 22% Kebl 21% Orie 2% Hert 0% Univ 0%
10Wolfson 6.4 +2.1 Ball 51% Kebl 26% Orie 10% Wolf 6% Hert 5% Chri 3%
11Hertford 5.8 -0.2 Hert 67% Orie 16% Ball 12% Kebl 5% NewC 0% Wolf 0%
12Oriel 6.0 +0.5 Orie 71% Hert 28% NewC 1% Kebl 0% Worc 0% Chri 0%
13Somerville 4.5 -2.3 NewC 85% Worc 11% Some 2% Jesu 1% Hert 0% Orie 0% Kebl 0% Linc 0%
1Merton 3.5 -3.9 Worc 68% Some 14% NewC 13% Jesu 5% Orie 0% Linc 0% Mert 0%
2New College 5.4 +1.9 Jesu 45% Some 38% Worc 16% NewC 1% Mert 0% Osle 0% Linc 0%
3Worcester 5.2 +1.8 Some 46% Jesu 38% Linc 12% Worc 5% NewC 0% Mert 0% Osle 0% Trin 0%
4Jesus 5.0 +1.3 Linc 86% Mert 13% Osle 1% Trin 0% Worc 0% Some 0% Jesu 0% SAnn 0%
5St Anne's 4.1 -2.3 Mert 87% Trin 11% Jesu 2% Linc 0% Worc 0% Osle 0%
6Osler House 4.3 -2.6 Trin 88% Jesu 10% Linc 1% Worc 1% Osle 1% SAnn 0% Some 0% Mert 0%
7Lincoln 5.6 +3.1 SAnn 75% Osle 15% SHug 7% Exet 1% Linc 1% Trin 1% SCat 0% Mert 0%
8St Catherine's 4.2 -2.5 Mans 57% SAnn 21% Osle 13% SHug 5% SCat 2% Exet 1% Linc 0%
9Trinity 5.6 +3.1 Osle 61% Mans 24% SHug 5% SAnn 4% SCat 4% Exet 2% Linc 0% Wad2 0%
10St Hugh's 4.4 -0.9 SCat 46% SHug 20% Mans 10% Osle 9% Lina 7% Exet 6% Wad2 1% SAnn 0%
11Exeter 4.4 -1.3 SCat 38% SHug 25% Lina 16% Exet 14% Mans 5% Wad2 2% Bras 0% Lady 0%
12Mansfield 5.3 +3.2 Lina 27% Exet 24% SHug 22% SCat 9% Lady 7% Wad2 4% Bras 4% Mans 2%
13Wadham II 4.0 -2.1 Lina 28% Exet 24% Bras 14% Lady 14% SHug 13% Wad2 5% Mans 1% Corp 1%
1Corpus Christi 3.7 -3.3 Bras 28% Exet 23% Lina 17% Wad2 13% Lady 12% SHug 3% Corp 3% Mans 1%
2Linacre 4.7 +2.5 Lady 36% Wad2 26% Bras 25% Corp 7% Lina 4% Exet 3% Wol2 0% Mans 0%
3Brasenose 4.6 +1.3 Wad2 41% Lady 27% Bras 23% Corp 6% Wol2 2% Lina 1%
4L.M.H. 4.8 +2.3 Wol2 57% Corp 28% Wad2 6% Bras 6% Lady 3% Quee 0% Lina 0% SHil 0%
5Queen's 3.2 -2.9 Corp 57% Wol2 40% SPet 1% Bras 1% Lady 1% Wad2 1% SHil 0% Quee 0%
6Wolfson II 4.3 +1.6 SPet 77% SHil 13% Quee 8% Wad2 1% Wol2 1% SAnt 1% Bras 0%
7St Peter's 3.9 +0.7 SHil 45% Quee 25% SPet 17% SAnt 12% Uni2 1% SJo2 0% Wol2 0%
8St Hilda's 3.7 +0.4 Quee 35% SAnt 28% SHil 19% Uni2 14% SPet 4% SJo2 0% Pem2 0%
9St John's II 3.0 -2.7 Quee 32% SAnt 26% Uni2 25% SHil 15% SJo2 1% Gree 0% SPet 0% Wor2 0%
10St Antony's 3.6 +0.9 Uni2 49% SAnt 21% SJo2 15% SHil 8% Pem2 4% CCh2 1% Wor2 1% Gree 0%
11University II 3.7 +1.4 Gree 65% Pem2 11% SJo2 11% Wor2 4% Uni2 3% CCh2 2% SAnt 2% SHil 1%
12Linacre II 2.9 -2.9 SJo2 58% Gree 25% SAnt 8% Uni2 5% Pem2 2% Wor2 1% CCh2 1% SHil 0%
13Worcester II 3.4 -1.3 Pem2 38% Wor2 25% SJo2 14% Lna2 7% Gree 7% SAnt 3% CCh2 3% Uni2 1%
1Pembroke II 3.8 +0.7 Lna2 31% Pem2 30% Wor2 28% CCh2 6% Mag2 3% Gree 1% SAnt 1% SJo2 0%

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Predicted Gains

Table shows the crews in decreasing order of predicted Gain in places for the week. Start is the crew's Wednesday starting position. (Eg if a crew has a 50% probability of rising one place and a 50% probability of rising two places, the predicted gain is +1.5.)

Men's Divisions Women's Divisions
CrewGainStartCrewGainStart
1Mans+3.321 1Trin+3.022
2Jesu+3.223 2Linc+2.720
3Quee+2.630 3Lady+2.630
4Pem2+2.426 4Wolf+1.910
5Mert+2.232 5Univ+1.8 8
6Lina+2.235 6Pem2+1.440
7Kebl+2.110 7Worc+1.416
8Wadh+1.913 8Magd+1.3 5
9NewC+1.715 9Mans+1.225
10Uni2+1.43810Uni2+1.137
11Hert+1.41411Orie+1.012
12SEH2+1.33712Wol2+1.032
13Magd+0.6 413Pemb+1.0 4
14Ori2+0.42414NewC+0.815
15Wolf+0.3 715Lina+0.728
16Chri-0.1 316Jesu+0.717
17Orie-0.1 117SPet+0.333
18Univ-0.3 618SJo2+0.235
19Some-0.42919Bras+0.229
20Bras-0.41820SHil-0.234
21Pemb-0.5 221Kebl-0.2 9
22Tri2-0.54022Hert-0.311
23Linc-0.51623Corp-0.527
24Ball-0.8 824Osle-0.519
25ChC2-0.82725Wad2-0.526
26Trin-0.9 526SJoh-0.5 2
27SJoh-1.01727Wadh-0.6 1
28New2-1.03328Lna2-0.838
29SEdm-1.11229Some-0.813
30SHug-1.23130SHug-1.023
31Mag2-2.03431Exet-1.124
32Corp-2.02832Chri-1.5 6
33Exet-2.02533Ball-1.6 7
34Worc-2.01134Quee-2.131
35Lady-2.01935SEdm-2.4 3
36SPet-2.12236SCat-2.621
37Wad2-2.23637Wor2-2.639
38SCat-2.3 938SAnn-3.018
39Exe2-2.53939SAnt-3.236
40SAnn-2.72040Mert-3.814


Contributor Statistics

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The following table shows the statistics for each contributor's score compared to the crew scores after the latest SAD iteration. Average error is the average difference, irrespective of sign, between the contributor's score and the current score, while the Bias is the average difference including sign (positive bias means contributor scores are higher than current scores).
TT represents the Torpids scores which are also included as an estimate.

       Pos#   Name   Avg.Error   Bias   No.estimates supplied
         1     CW      .136     -.079        14
         2     AB      .248      .042        31
         3     RC      .286     -.070        76
         4     SH      .342      .184        19
         5     AD      .346      .238        13
         6     JW      .386     -.100        14
         7     TT      .525      .010        80

How to Contribute Information

To supply a score, just decide what sort of standard each crew seems to be, based on the following scale:

Within the SAD program, a difference of 0.4 corresponds to 1.5 lengths quicker over the course, ie a bump is expected at the finish line.

Don't feel obliged to supply an assessment for every crew - just anything you're confident about, even if they are similar to the numbers already listed (it adds weight to the estimate). Also, you can revise your estimates at a later date, in which case I'll remove your earlier estimate for any particular crew. I don't accept scores of your own college.

Normally I will list contributors by their initials (or any other 2-letter acronym you wish to be known by) at the top of this page, but I won't give out any other information on your identity or which crews you have assessed.

Anyone who contributes information will receive the current list of scores for their own college (scores only - contributor codes removed).

New contributors will have a weight +/-0.5 assigned to their estimate. Those who contributed in Eights 2013 will have their scores weighted by their average error, limited to range 0.2-0.5

Email scores to dudhia@atm.ox.ac.uk


The Gory Details

The SAD program calculates a statistical average of the results of 10000 runs of Bumps. In each run the crew speed is varied by some random amount about the mean speed listed (in brackets), the 1-sigma variation depending on the number, accuracy and time of estimates supplied by contributors. This allows for errors in the assessed speed, but within each `day' of the Bumps, there is an additional term to allow for random variations in a crew's performance from day to day, varying from +/-0.2 for 1st Division crews to +/-0.4 for 3rd Division.
The program allows for overbumps, Sandwich boats, and separate rules for Torpids and Eights, but makes no allowance for crews below those listed.
FORTAN source code.

Contributor estimates are each given a weight of +/-0.5, but those who proved more accurate last Torpids will have those errors used instead. These weights apply for the iteration in which the score was used, but on subsequent iterations all the older scores are reduced in weight (i.e. recent estimates carry more weight).


SAD BaStaRD

(SAD Bayesian Statistical Revised Distribution)

Once racing gets under way, I'll start running SAD BaStaRD (PS Thanks to Tom Fleming for the acronym) to `tune' the actual estimates to values that best fit the results of each day's racing.

The SAD BaStaRD program runs the SAD program and calculates the probability of the actual outcome of each day's racing using the initial scores. It then perturbs each crew's score by +/-0.1, and also the uncertainty in the score by +/-0.1, and recalculates the probability. Whichever perturbation leads to the greatest probability is kept, and the process then repeated. This is continued until, for a given set of scores, all further perturbations result in a lower probability for the actual outcome, and these scores are then taken as the best.

The final result should be scores which best represent each crew's true speed as well as give a means of evaluating the accuracy of each contributor.

If a crew bumps each day, the score that would give the actual outcome with the greatest probability is infinity, so to keep things sensible the original SAD estimates and their uncertainties are used as an a priori constraint.