S.A.D. Predictions - Eights 2014

Iteration#2: 11th May

This is the second iteration containing contributions from SG, AA, JW, CW, AD, HC, BD.

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 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).


Men's Divisions 1-3

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Pos Start Crew Score Av.Rise Finishing Crew
1Pembroke 6.7 -0.5 Pemb 61% Orie 27% Chri 11% SCat 0%
2Christ Church 6.5 -0.5 Chri 38% Orie 30% Pemb 30% Magd 1% SCat 0% Wolf 0% Univ 0%
3Oriel 6.8 +0.8 Chri 39% Orie 36% Magd 11% Pemb 7% SCat 6% Wolf 2% Univ 0%
4University 5.8 -1.7 Magd 41% Wolf 19% Univ 15% Chri 10% SCat 7% Orie 6% Pemb 2% Trin 1%
5Wolfson 6.0 -0.8 Univ 33% Magd 25% Wolf 23% SCat 12% Trin 5% Chri 1% Orie 1% Pemb 0%
6Magdalen 6.4 +1.4 Wolf 27% Univ 27% Magd 16% SCat 13% Trin 11% Worc 5% Ball 0% Chri 0%
7St Catherine's 6.0 -0.1 Trin 22% SCat 22% Wolf 20% Univ 16% Worc 10% Magd 5% Hert 3% Ball 1%
8Trinity 6.0 +0.3 Trin 36% Worc 21% SCat 15% Wolf 8% Univ 8% Ball 6% Hert 5% Magd 1%
9Balliol 5.5 -1.7 Worc 31% Ball 17% Trin 16% Kebl 14% Hert 9% SCat 9% SEdm 2% Wolf 2%
10Worcester 6.0 +1.0 Kebl 29% Ball 17% Worc 16% Hert 14% SCat 8% Trin 6% SEdm 6% Wadh 4%
11Hertford 5.6 -0.7 Ball 24% Kebl 23% Hert 13% SEdm 11% Worc 10% SCat 8% Wadh 6% SJoh 3%
12St Edmund Hall 5.6 -0.7 Ball 21% SEdm 20% Hert 19% Kebl 19% Wadh 10% SJoh 6% Worc 5% Trin 0%
13Keble 6.1 +2.0 SEdm 31% Hert 17% Ball 13% Wadh 13% Kebl 10% SJoh 8% NewC 6% Worc 2%
1Wadham 5.5 +0.1 Wadh 32% SEdm 24% SJoh 16% Hert 13% NewC 6% Linc 4% Kebl 4% SAnn 1%
2Lincoln 4.6 -2.4 SJoh 27% Wadh 20% NewC 15% Linc 11% SAnn 10% Hert 7% SEdm 6% Bras 2%
3St John's 5.3 +0.6 Lady 21% SAnn 21% NewC 16% Linc 14% SJoh 13% Wadh 7% Bras 7% SEdm 0%
4St Anne's 5.0 -0.5 Lady 28% SAnn 20% Linc 16% NewC 11% Bras 10% SJoh 8% Wadh 7% Exet 0%
5New College 5.2 +0.5 Lady 27% Linc 19% SAnn 17% Bras 10% NewC 9% Mans 8% SJoh 6% Exet 1%
6Brasenose 5.0 -0.5 Linc 35% SAnn 16% Bras 11% Lady 10% NewC 9% Mans 8% SJoh 7% Exet 2%
7L.M.H. 5.5 +2.3 Bras 29% Mans 17% NewC 12% SAnn 11% Lady 10% Jesu 6% Exet 6% SJoh 5%
8Exeter 4.3 -2.2 Mans 21% Bras 20% Jesu 18% ChC2 14% Exet 11% NewC 9% SAnn 3% Lady 3%
9Mansfield 4.9 +0.3 ChC2 29% Jesu 24% Exet 13% Mans 13% Bras 8% NewC 6% SPet 4% Some 1%
10Jesus 4.8 +0.2 ChC2 31% Jesu 21% Exet 14% SPet 10% Mans 9% Pem2 6% Some 5% Bras 3%
11Christ Church II 5.0 +1.3 Exet 19% Pem2 18% SPet 15% ChC2 13% Some 12% Jesu 12% Mans 6% Ori2 5%
12Somerville 4.5 -1.2 Exet 33% Pem2 15% Some 11% Jesu 10% SPet 10% Mans 8% ChC2 7% Ori2 4%
13St Peter's 4.7 +0.0 Pem2 24% Some 23% SPet 15% Mans 9% Ori2 8% Jesu 6% Corp 5% Mert 4%
1Pembroke II 4.9 +1.1 Some 26% Pem2 21% SPet 20% Corp 12% Ori2 12% Quee 3% Mert 3% Jesu 3%
2Oriel II 4.4 -0.5 Corp 24% Some 16% Ori2 16% SPet 15% Pem2 10% Quee 10% Mert 9% SHug 0%
3Corpus Christi 4.5 +0.3 Corp 27% Quee 19% Ori2 18% Mert 13% SPet 8% Some 6% Pem2 4% New2 3%
4Queen's 4.3 -0.3 Quee 25% Corp 19% Mert 18% Ori2 16% New2 10% SHug 4% SEH2 4% SPet 3%
5Merton 4.3 +0.2 Lina 28% New2 16% Quee 15% Mert 12% Ori2 9% SEH2 7% Corp 7% SHug 6%
6St Hugh's 3.7 -1.9 Lina 21% New2 17% Mert 15% Quee 15% Ori2 10% SHug 9% SEH2 7% Corp 4%
7New College II 4.2 +0.4 New2 23% Lina 20% SHug 15% Mert 12% Uni2 11% SEH2 10% Quee 8% Corp 1%
8St Edmund Hall II 3.9 -0.8 SHug 20% Uni2 17% New2 16% SEH2 15% Lina 13% Mert 10% Mag2 3% Quee 3%
9Linacre 4.6 +2.2 SHug 20% Tri2 19% Uni2 16% SEH2 12% New2 9% Mag2 8% Lina 7% SAnt 6%
10University II 4.0 +0.2 SHug 24% SEH2 15% Tri2 15% Uni2 14% SAnt 10% Mag2 7% New2 5% Lina 5%
11St Antony's 3.7 -0.8 Tri2 19% SAnt 18% Uni2 18% SEH2 16% Mag2 10% Wad2 7% Bal2 5% Lina 4%
12Magdalen II 3.6 -0.7 SAnt 25% SEH2 14% Tri2 13% Uni2 12% Mag2 12% Wad2 9% Bal2 7% SCa2 4%
13Trinity II 4.1 +1.4 SAnt 23% Mag2 16% Wad2 14% Tri2 12% Bal2 11% SCa2 9% Uni2 6% Wor2 5%
1Wadham II 3.5 -0.3 Mag2 20% Wad2 20% Bal2 15% SAnt 12% Tri2 11% SCa2 10% Wor2 6% Uni2 3%

Women's Divisions 1-3

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Pos Start Crew Score Av.Rise Finishing Crew
1St John's 6.5 -1.0 SJoh 50% Wadh 32% SEdm 17% Magd 1% Pemb 0%
2Wadham 6.5 -0.2 Wadh 38% SEdm 26% SJoh 24% Magd 8% Pemb 4% Ball 0%
3St Edmund Hall 6.4 +0.1 SEdm 29% Magd 23% Wadh 19% Pemb 14% SJoh 13% Chri 2% Ball 1%
4Pembroke 6.0 -0.8 Magd 30% Pemb 24% SEdm 14% SJoh 8% Wadh 8% Univ 7% Chri 5% Ball 3%
5Magdalen 6.3 +0.8 Pemb 26% Magd 22% Univ 15% Ball 12% Chri 9% SEdm 7% SJoh 6% Wadh 3%
6Balliol 5.9 -0.7 Ball 28% Univ 22% Pemb 19% Chri 14% Magd 11% SEdm 4% Mert 1% Wadh 1%
7Christ Church 5.9 -0.3 Ball 31% Univ 24% Chri 17% Kebl 10% Pemb 9% Magd 4% Mert 3% SEdm 2%
8University 6.2 +1.3 Chri 28% Univ 22% Ball 20% Kebl 11% Mert 9% Hert 5% Pemb 3% Magd 1%
9Hertford 5.5 -1.1 Hert 28% Mert 20% Chri 17% Kebl 15% Univ 8% Ball 5% Orie 4% Wolf 2%
10Merton 5.6 -0.4 Hert 34% Mert 20% Kebl 15% Orie 14% Wolf 7% Chri 6% Osle 1% Univ 1%
11Keble 5.7 +0.3 Orie 22% Hert 21% Mert 17% Wolf 14% Kebl 13% Worc 8% Chri 2% Osle 1%
12Oriel 5.6 +0.2 Orie 26% Wolf 20% Mert 14% Kebl 12% Worc 10% Hert 9% SCat 3% Some 3%
13Wolfson 5.6 +0.4 Wolf 24% Orie 21% Worc 15% Mert 9% Kebl 9% Some 9% SCat 7% Osle 3%
1Somerville 5.2 -0.9 Some 24% Wolf 22% Worc 17% Orie 10% Kebl 9% SCat 7% Osle 6% Mert 5%
2Osler House 4.7 -2.0 Some 30% Worc 17% SCat 16% NewC 11% Osle 7% Wolf 7% Kebl 6% Jesu 4%
3Worcester 5.5 +1.4 NewC 30% Some 20% SCat 16% Worc 13% Osle 10% Jesu 9% Wolf 2% Orie 0%
4St Catherine's 5.2 +0.3 NewC 29% Osle 17% SCat 16% Jesu 16% Some 11% Worc 9% SAnn 2% Wolf 0%
5Jesus 5.0 -0.3 Jesu 24% Osle 23% NewC 20% SCat 13% SAnn 11% Worc 6% Some 2% Linc 1%
6New College 5.5 +2.1 Osle 29% Jesu 22% SAnn 14% SCat 11% Lina 10% NewC 7% Linc 4% Worc 3%
7Exeter 4.1 -3.0 SAnn 25% Lina 22% Jesu 16% Linc 15% SCat 9% Trin 6% NewC 3% Exet 2%
8St Anne's 4.8 +0.3 SAnn 21% Lina 21% Linc 18% Trin 15% Exet 8% Jesu 6% Mans 6% SCat 4%
9Lincoln 4.7 -0.3 Trin 20% Exet 20% Linc 20% Lina 16% Mans 11% SAnn 9% Jesu 2% Wad2 1%
10Linacre 5.0 +1.2 Exet 32% Mans 16% Trin 16% Linc 10% Lina 9% SAnn 6% Wad2 5% SHug 5%
11Trinity 4.9 +0.7 Exet 37% Linc 13% Mans 12% Trin 10% Lina 8% SAnn 7% Wad2 6% SHug 5%
12Mansfield 4.8 +0.5 Mans 22% Trin 17% Wad2 14% Linc 13% SHug 11% Lina 9% Corp 6% SAnn 4%
13Wadham II 4.5 -0.4 Wad2 21% Mans 18% SHug 15% Corp 12% Trin 10% Linc 5% Quee 5% SHil 5%
1Queen's 4.1 -1.8 Wad2 27% SHug 17% Corp 16% Quee 15% Mans 11% SHil 5% Trin 5% Bras 3%
2St Hugh's 4.5 +0.4 Quee 18% Corp 17% Wad2 15% Lady 14% SHug 12% Bras 10% SHil 9% Mans 3%
3Corpus Christi 4.5 +0.6 Quee 25% Lady 18% Corp 14% SHug 10% Bras 10% SHil 10% Wad2 8% SJo2 3%
4St Hilda's 4.2 -0.5 Quee 23% Lady 17% Corp 13% SHug 12% SHil 11% Bras 10% SJo2 7% Wol2 4%
5Brasenose 4.2 -0.2 SHil 16% Lady 15% Bras 14% Corp 12% Quee 12% SJo2 12% SHug 10% Wol2 7%
6L.M.H. 4.5 +1.1 SPet 18% SHil 16% SJo2 14% Bras 14% Lady 12% Wol2 11% Corp 6% SAnt 5%
7St John's II 4.0 -0.4 SPet 27% SHil 15% Bras 14% SJo2 12% Wol2 11% Lady 9% SAnt 7% Pem2 2%
8Wolfson II 3.9 -0.4 SPet 23% SJo2 15% Wol2 13% Bras 13% SAnt 8% SHil 8% Lady 8% Pem2 7%
9St Antony's 3.7 -1.1 SJo2 17% Wol2 17% SPet 15% SAnt 14% Pem2 12% Bras 8% CCh2 8% Lady 5%
10St Peter's 4.4 +2.0 SAnt 17% Wol2 16% Pem2 15% CCh2 12% SJo2 12% SPet 9% Lna2 9% Wor2 5%
11Pembroke II 3.7 -0.4 SAnt 19% Pem2 14% Wol2 13% CCh2 13% Lna2 11% Wor2 10% SJo2 8% Her2 5%
12Christ Church II 3.6 -0.2 SAnt 18% Wor2 15% Pem2 15% CCh2 14% Lna2 12% Her2 9% Uni2 6% Wol2 6%
13Linacre II 3.5 -0.4 Wor2 16% Pem2 15% CCh2 14% Lna2 14% SAnt 11% Her2 11% Uni2 9% Mer2 5%
1Worcester II 3.6 +0.3 Wor2 20% CCh2 17% Lna2 17% Her2 14% Pem2 12% Uni2 10% Mer2 6% Lin2 3%

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.)

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Men's Divisions Women's Divisions
CrewGainStartCrewGainStart
1Lady+2.320 1NewC+2.119
2Lina+2.235 2SPet+2.036
3Kebl+2.013 3Worc+1.416
4Magd+1.4 6 4Univ+1.3 8
5Tri2+1.439 5Lina+1.223
6ChC2+1.324 6Lady+1.132
7Pem2+1.127 7Magd+0.8 5
8Worc+1.010 8Trin+0.724
9Orie+0.8 3 9Corp+0.629
10SJoh+0.61610Mans+0.525
11NewC+0.51811SHug+0.428
12New2+0.43312Wolf+0.413
13Mans+0.32213SCat+0.317
14Trin+0.3 814Wor2+0.340
15Corp+0.32915SAnn+0.321
16Mert+0.23116Kebl+0.311
17Jesu+0.22317Orie+0.212
18Uni2+0.23618SEdm+0.1 3
19Wadh+0.11419Wadh-0.2 2
20SPet+0.02620Bras-0.231
21SCat-0.1 721CCh2-0.238
22Quee-0.33022Linc-0.322
23Wad2-0.34023Chri-0.3 7
24Ori2-0.52824Jesu-0.318
25Bras-0.51925Pem2-0.437
26Pemb-0.5 126Mert-0.410
27SAnn-0.51727Lna2-0.439
28Chri-0.5 228Wol2-0.434
29Hert-0.71129SJo2-0.433
30SEdm-0.71230Wad2-0.426
31Mag2-0.73831SHil-0.530
32Wolf-0.8 532Ball-0.7 6
33SAnt-0.83733Pemb-0.8 4
34SEH2-0.83434Some-0.914
35Some-1.22535SJoh-1.0 1
36Univ-1.7 436Hert-1.1 9
37Ball-1.7 937SAnt-1.135
38SHug-1.93238Quee-1.827
39Exet-2.22139Osle-2.015
40Linc-2.41540Exet-3.020


Contributor Statistics

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).
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       Pos#   Name   Avg.Error   Bias   No.estimates supplied
         1     SG      .093      .004        27
         2     AA      .167      .033         6
         3     BD      .171      .114         7
         4     TT      .200     -.027        80
         5     HC      .222     -.189        18
         6     CW      .273     -.100        22
         7     AD      .333      .195        39
         8     JW      .400      .067         9


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.