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Wuornos
Dec 9th, 2007, 01:08 PM
Although in many respects these ratings are more elementary in their calculation methodology than previous exercises I have undertaken they seek to better represent and model the thought processes of expert opinion in the field of tennis

They are called the DOT ratings because the model developed is based around three factors. The level of Domination of the rated player meaning the concentration of achievement within a limited time frame. Standard of Opposition that are currently active when achieving their measured domination. Tournament being competed in and its importance measured by the players attracted in recent years.

The DOT system is what I would describe as a double iterative process. We will come to exactly what this means shortly.

Achievement is measured on a very basic formula, but should be fit for our purpose. i.e. Players in the majors receive points based on their round of exit. Each round they progress earns them double the points of the previous round. I have never been a believer in the official ratings approach of the progression of a round within an event being worth less than double achievement. If the player numbers halve in my eyes the achievement doubles, hence the above approach. The value of the numbers are irrelevant as this does not effect the relative rankings. Some will notice I am only looking at majors and this is because I have previously received feedback highlighting the fact that some players do not consider the lesser events as important and their performance given the heavy schedule is weakened within these events. Of course Achievements measured in this way would massively favour players like Connors and Agassi, who both had exceptionally long careers, while penalising players like Borg and Laver (who had short careers within the open era).

Next we move onto Domination. Domination is calculated as rolling figure based upon achievement within recent events with more recent events receiving greater weight. Achievement points from the last 4 Majors receive the highest weighting while each year the weighting awarded to the event halves. As you can see more than half of a players dominance is made up of his/her performance in the last 12 months with the remainder being made up of performances over the previous years.

These simple calculations generating a very simple estimate of a players domination ends the first iteration.

The second iteration begins by calculating event weightings based upon the player dominations calculated as part of the first iterative process. Event weightings are reflective of the strength of the tournament. Of course the strength of any tournament is dependant on the players current strength of the world players multiplied by the events ability to attract them. This sounds very complex but in reality the calculation is simple. The average domination score for all players taking part in the event as calculated in the first iteration is sufficiently accurate for our purposes . Remember this implicitly includes player strength and the tournaments status. E.g. If the overall domination points reduce at the top of the player population then the tournament strength reduces proportionately. Likewise if a tournament begins to fail in attracting the top players while dominance levels amongst the top players remain constant, then again we see the tournament strength drop. The results from these calculation lead to the Australian Open receiving less weighting in the mid to late 1970s and early 1980s while the French has also suffered at times. Wimbledon and the US Open remain reasonably high in these calculations. Please note the above methodology ensures the weighting remains directly proportional to the domination of players attracted and therefore is self adjusting and free from human opinion.

The next step in the process is to recalculate the domination ratings. These are calculated in exactly the same way as previously, i.e. achievement multiplied by the year weightings except each is then also multiplied by the relevant tournament strength. This figure then provides a basic indicator of current dominance adjusted by tournament status and dominance of other top players. One piece of feedback I have received in relation to this is that it is slightly self referencing. That is a tournament is stronger if Federer competes and therefore Federer always receives that benefit. I agree with this but do not see it as a problem, it is important that everyone receives the same credit for winning an event and therefore to exclude the player being rated from the strength calculation of that tournament would be equally unfair. The feedback is limited and results only in a slight damping of the rating changes at the top of the scale, which is not something I would necessarily see as a bad thing. The benefits are massive in that we have an independent measure which combines player strength with tournament status which is a big stumbling block in many ratings which give equal weight to all majors irrespective of era and their status at that time.

For the very early periods of the open era it is necessary to use a standard statistical tool to provide a cautious estimate of the domination score had a full 4 years data been available. To do this we take the total weighting which is normally applied to players.

As we can see we now have an adjusted dominance rating for the point in time we have calculated. This gives an indication of the players strength in majors at that point and that point only. Most people assess players on their abilities when they are at their peaks and it is therefore necessary to recalculate the ratings after each major event to identify correctly their peak playing strength.

In the real world an arithmetic progression in standard would yield a geometric increase in dominance. For this reason, ratings have been standardised to a linear scale. They have also been adjusted to reflect a particular standard. The standard used is the minimum level of play necessary to achieve a major quarter final when the standard or dominance at the top of the professional game is at its lowest. This standard has been set at 2500. By and large players who can exceed this standard by a clear 200 points, i.e. 2700, are those players who can expect to win 4 or more majors in an average length career. Of course some players over achieve while others under achieve so this is not a hard and fast rule.

I have taken great time and trouble to ensure the adjustments for tournament strength, which are effected by the standard of the top players in the population and the respective tournament status, are precisely balanced. A player existing in the general population stands an equal chance of increasing or decreasing in rating following the arrival within the population of an outstanding player. Any increase is therefore due to a change in the actual players standard as the reduction in iteration 1 dominance points is balanced by the tournament weightings in the second iteration. A good example of this is Andy Roddick. When he won the US Open in 2003 he had a DOT rating of 2630. In 2004 Federer’s domination of the mens’ game began, but at the end of that year Roddick’s rating had bearly moved at all despite the reduced opportunities in majors. His rating was 2629. 2005 and Rafael Nadal won his first major along with Safin, but Andy Roddick was improving slightly at this time and his rating edged up to 2636. 2006 saw Federer and Nadal take over the top of the men’s game completely. Despite this domination, Roddick’s rating was stable at 2638. Finally in 2007 Roddick’s rating has remained exactly the same at 2638. I hope this reassures some people concerning the validity of the adjustments made to the ratings balancing the relative increase or decrease in rates of dominance by other players at the top of the game.

I hope you all enjoy these ratings as much as I have in putting them together. Any questions please ask. Or should you just wish to know about an individual players peak rating or how their rating progressed over time, who were the top players at what time etc, then just ask away.

I certainly don’t expect this to answer the GOAT question but at least it should help provide some informed discussion over and above personal opinion and based on ‘value added’ statistical data.

I am seeking a publisher for a book giving a more detailed anlaysis relating to methodology and outputs of these data early next year. If you are in position to help me, please get in touch.

Take care all

Tim :)

Wuornos
Dec 9th, 2007, 01:17 PM
The following list shows the Top 100 Women Singles Players of the open era.

The first figure is their rank, second entry is the name of the player, the third entry shows the peak DOT Rating achieved based only on data from the open era, and the final four figures are the number of majors won, the number of major finals lost, the number of major semi finals lost and the number of major quarter finals lost, all within the open era.

Where two ratings are the same but the rank is different this is because each DOT Rating is rounded to the nearest whole number and one rating will be marginally higher than the other.

Similar ratings are available for men.

Ratings correct up to and including US Open of 2007.

1 Steffi Graf 2872 22 9 6 5
2 Martina Navratilova 2871 18 14 12 9
3 Monica Seles 2827 9 4 5 13
4 Margaret Smith Court 2824 11 1 4 4
5 Chris Evert 2816 18 16 18 2
6 Serena Williams 2786 8 2 2 9
7 Arantxa Sánchez Vicario 2760 4 8 10 13
8 Martina Hingis 2750 5 7 7 5
9 Billie Jean King 2746 8 4 5 11
10 Hana Mandlíková 2742 4 4 6 9
11 Venus Williams 2740 6 6 4 10
12 Evonne Goolagong 2738 7 11 4 4
13 Justine Henin 2736 7 4 5 1
14 Lindsay Davenport 2720 3 4 11 13
15 Gabriela Sabatini 2716 1 2 15 10
16 Jennifer Capriati 2703 3 0 10 10
17 Ann Jones 2699 1 2 3 0
18 Amélie Mauresmo 2690 2 1 5 9
19 Maria Sharapova 2684 2 1 6 2
20 Helena Suková 2680 0 4 3 11
21 Kim Clijsters 2680 1 4 7 2
22 Conchita Martínez 2672 1 2 9 11
23 Mary Joe Fernández 2669 0 3 6 8
24 Andrea Jaeger 2667 0 2 5 3
25 Mary Pierce 2666 2 4 0 8
26 Jana Novotná 2665 1 3 5 13
27 Tracy Austin 2661 2 0 3 8
28 Zina Garrison 2656 0 1 4 10
29 Nancy Richey 2656 1 1 4 4
30 Rosemary Casals 2653 0 2 4 10
31 Virginia Wade 2649 3 0 6 12
32 Claudia Kohde-Kilsch 2641 0 0 4 5
33 Iva Majoli 2639 1 0 0 5
34 Olga Morozova 2636 0 2 1 7
35 Kerry Reid 2636 1 2 6 10
36 Pam Shriver 2634 0 1 8 10
37 Kathy Jordan 2625 0 1 1 2
38 Svetlana Kuznetsova 2623 1 2 0 5
39 Anastasia Myskina 2620 1 0 0 5
40 Karen Krantzcke 2618 0 0 3 5
41 Wendy Turnbull 2617 0 3 4 7
42 Kimiko Date 2614 0 0 3 3
43 Judy Tegart 2613 0 1 1 6
44 Jo Durie 2610 0 0 2 2
45 Sue Barker 2610 1 0 3 2
46 Manuela Maleeva 2606 0 0 2 12
47 Mima Jaušovec 2606 1 2 2 5
48 Helga Niessen Masthoff 2606 0 1 3 6
49 Betty Stöve 2605 0 1 1 1
50 Catarina Lindqvist 2604 0 0 2 3
51 Carling Bassett-Seguso 2604 0 0 1 3
52 Helen Gourlay 2604 0 2 3 3
53 Françoise Durr 2603 0 0 3 5
54 Renáta Tomanová 2602 0 2 1 3
55 Amanda Coetzer 2602 0 0 3 4
56 Julie Heldman 2602 0 0 3 5
57 Lori McNeil 2601 0 0 2 2
58 Winnie Shaw 2601 0 0 2 2
59 Yelena Dementieva 2600 0 2 2 2
60 Virginia Ruzici 2599 1 1 1 8
61 Ana Ivanović 2597 0 1 1 1
62 Maria Bueno 2596 0 0 1 2
63 Kathy Rinaldi 2596 0 0 1 2
64 Lesley Hunt 2595 0 0 1 7
65 Dianne Fromholtz 2594 0 1 3 2
66 Sylvia Hanika 2592 0 1 0 5
67 Katerina Maleeva 2591 0 0 0 7
68 Natasha Zvereva 2590 0 1 1 6
69 Nadia Petrova 2590 0 0 2 4
70 Nathalie Tauziat 2587 0 1 0 6
71 Lesley Turner Bowrey 2585 0 0 1 4
72 Anke Huber 2585 0 1 2 4
73 Nicole Vaidišová 2584 0 0 2 2
74 Barbara Potter 2582 0 0 1 4
75 Daniela Hantuchová 2581 0 0 0 3
76 Kazuko Sawamatsu 2581 0 0 1 3
77 Anna Chakvetadze 2581 0 0 1 2
78 Paola Suárez 2581 0 0 1 3
79 Jelena Janković 2580 0 0 2 1
80 Claudia Porwik 2578 0 0 1 1
81 Annette Du Plooy 2578 0 0 1 0
82 Gigi Fernández 2576 0 0 1 2
83 Belinda Cordwell 2573 0 0 1 0
84 Anne Smith 2573 0 0 0 3
85 Camille Benjamin 2573 0 0 1 0
86 Chris O'Neil 2573 1 0 0 0
87 Chanda Rubin 2573 0 0 1 3
88 Marion Bartoli 2572 0 1 0 0
89 Irina Spîrlea 2572 0 0 1 1
90 Judith Wiesner 2571 0 0 0 2
91 Meredith McGrath 2570 0 0 1 0
92 Bettina Bunge 2568 0 0 1 1
93 Rosalyn Fairbank 2568 0 0 0 2
94 Brenda Schultz-McCarthy 2568 0 0 0 2
95 Gretchen Rush 2565 0 0 0 2
96 Janet Newberry 2565 0 0 2 2
97 Marianne Werdel-Witmeyer 2565 0 0 1 0
98 Yvonne Vermaak 2564 0 0 1 0
99 Patty Schnyder 2564 0 0 1 4
99 Fabiola Zuluaga 2564 0 0 1 0


I hope you all enjoy the ratings and feel free to ask any questions should you wish.

Take care all

Tim

AnnaK_4ever
Dec 9th, 2007, 03:29 PM
I don't believe any rating that puts Seles ahead of Evert, Sabatini ahead of Capriati, Fernandez ahead of Pierce, Jaeger ahead of Austin and so on.

Wuornos
Dec 9th, 2007, 06:31 PM
I don't believe any rating that puts Seles ahead of Evert, Sabatini ahead of Capriati, Fernandez ahead of Pierce, Jaeger ahead of Austin and so on.

That's great. If you could possibly see yourself to provide a reason as to why you hold these views it may help me with the algorithm and methodology of DOT.

E.g., to choose one of your examples, Evert v Seles. Evert scored 12 majors but against reduced opposition in the first part of her career up to the US Open of 1981. However, with the emergence of Navratilova, Evert raised her game and while not getting the better of Navrtailova still scored 6 majors. These 6 majors in the light of the competition faced from Navratilova are evidence of a higher standard of play than the 12 majors she won in the first half of her career.

Seles on the other hand scored 9 majors and dominated Graf for a period of 2 years prior the the unfortunate stabbing incident. DOT evaluates this performance as being superior to that standard shown by Evert against Navratilova. However both performances are outstanding.

DOT therefore concludes that while Chris won more majors than Monica, her career was much longer and a significant part of which was against less dominant players than Graf or Navratilova. Graf therefore edges the DOT Rating by 15 points.

Thanks for the interest and look forward to receiving your reasons soon.

Regards

Tim

preacherfan
Dec 9th, 2007, 09:26 PM
Evert won 18 Slams.
Austin won 2 USO's - zero Slams for Jaeger.
Chris O'Neil #77 - won an Australian Open with a field that would struggle to make Tier III status today. She probably never even finished a year in the top 50.
Renata Tomanova is #54. She was r/u in two very pitiful Slam fields. Meanwhile, #55 Virginia Ruzici was in the top 12 or 15 in the world and made several Slam QF's or better. There is no comparison.
Belinda Cordwell and Camille Benjamin who had freak runs to Slam SF's are on the list. No way.

Winnie Shaw and Helen Gourlay were never top ten players. How are they higher than Maleeva, Dementieva, Fromholtz, Hanika, Tauziat?

Sorry, there are too many weak arguments in your rankings.

Wuornos
Dec 10th, 2007, 05:47 AM
Evert won 18 Slams.
Austin won 2 USO's - zero Slams for Jaeger.
Chris O'Neil #77 - won an Australian Open with a field that would struggle to make Tier III status today. She probably never even finished a year in the top 50.
Renata Tomanova is #54. She was r/u in two very pitiful Slam fields. Meanwhile, #55 Virginia Ruzici was in the top 12 or 15 in the world and made several Slam QF's or better. There is no comparison.
Belinda Cordwell and Camille Benjamin who had freak runs to Slam SF's are on the list. No way.

Winnie Shaw and Helen Gourlay were never top ten players. How are they higher than Maleeva, Dementieva, Fromholtz, Hanika, Tauziat?

Sorry, there are too many weak arguments in your rankings.

Thanks PreacherFan

You're the one person I was hoping would reply as I have read your other posts and have enjoyed them very much.

You've certainly made a lot of points. I'll try to take each one in turn.

'Evert won 18 Slams'. Yes that's right. 12 in the period before Navratilova hit her stride and 6 afterwards. As DOT adjusts for Opposition it was while she was scoring the 6 that she played her best quality of tennis.

'Austin won 2 USO's - zero Slams for Jaeger'. Yes, but DOT looks at more than just the the total number of majors won in producing it's Peak Rating. E.g. both only made 2 major finals and Jaeger made it to 7 Semi Finals compared with Tracy's 5. The thing that most influences DOT though, which remember is deriving the PEAK playing standard is that Jaegar made the Semi Finals of 4 majors on the trot ending with Wimbledon of 1983. When Tracey was at her peak she was more prone to lose in the quarter finals compare 8 losses to Jaegar's 3. DOT always looks at the losses as well as the wins as to do otherwise presents a lopsided picture.

'Chris O'Neil #77 - won an Australian Open with a field that would struggle to make Tier III status today. She probably never even finished a year in the top 50'. Yes that's absolutely correct. DOT uses an algorithm that adjusts the weighting of Tournaments based upon it's calculation of the strength of players present and the consistency of the tournament in recent years as an indicator of the world scene. In the year you select DOT calculated a weighting for the AO based on strength of only 1/3rd that of the other majors. Just to put things into perspective though. Yes Chris O'Neil won a weak major but rated above her are 42 players who never won any majors, but performed better at events with a greater automated weighting, inc Andrea Jaegar.

'Renata Tomanova is #54. She was r/u in two very pitiful Slam fields. Meanwhile, #55 Virginia Ruzici was in the top 12 or 15 in the world and made several Slam QF's or better. There is no comparison.'.
Yes agreed again, but first of all see above for Chris O'Neil. Who managed to win a against a 'pitiful' major field. All DOT is saying is taking into account that she finished runner up in two consecutive major's albeit with reduced strength and allowing for the fact she also had to face Evonne Goolagong in one of those finals, the evidence for her having a higher playing strength than Chris O'Neil is probably better. Remember that 54th best peak in the open era is not that high for someone who appeared in two consecutive major finals. This is because DOT has devalued those results. Also remember that DOT is rating 8 players above Renata who only made it to 1 major final. In comparing Tomanova with Virginia Ruzici you are absolutely correct in sayin that Virginia Ruzici total achievements were greater, after all she won one major and made 1 major final, both being the French open but two years apart and also lost out in a further major Semi Final and no fwere that 8 Quarter Finals. This of course compares with Tomanova having lost in 1 major semif final and 3 major quarter finals other than her two final appearances. To be honest what DOT is saying is that there is almost nothing to pick between these two players but looking at the fact that Tomanova's best results were in weaker tournaments than Ruzici's but were more concentrated in time the Peak standard is probably very similar.

If DOT did not take this approach of looking for Peak playing standard rather than total achievement some players careers would be underrated because of a very short career, e.g. Monica Seles.


'Belinda Cordwell and Camille Benjamin who had freak runs to Slam SF's are on the list. No way'. Laugh! Yes, well DOT cannot differentiate between freak runs and any other kind of runs for that matter. They really aren't very high on the list you know. As we are only looking at the open era, only 114 players have made major semi finals. We have to leave some room for those who 'freaked' it against weaker fields. Seriously though ranking them where they are isn't really saying that much. Sorry Belinda / Camille.

Winnie Shaw and Helen Gourlay were never top ten players. How are they higher than Maleeva, Dementieva, Fromholtz, Hanika, Tauziat? At last a point that I can answer quickly. These ratings are based on open era only but these two players' peaks were before the rankings began in 1975. No surprise then that they weren't top 10 players.

'Sorry, there are too many weak arguments in your rankings'. You've made some great points, PreacherFan. I have previously discussed this methodology within other forums and it took me months to pursuade people I was genuine and explain the intracicies and vagaries of the DOT system. To be honest your points are far better than many I have encountered, many are just plain abusive because the rankings don't say what they want them to say. To be honest they don't say what I want them to say either! (I'm a Monica Seles fan. However, they are statistically independent and free from human opinion or interference. i.e. all weightings for tournaments and strength of opposition are calculated by DOT itself usinga double itterative process and the methodologies adopted are statistically sound. As long as you remember we are talking peak ratings and not total achievement and that every rating is adjusted for strength of opposition and status of tournament, you can't go to far wrong in their interpretation. Just remember DOT stands for (D)omination x (O)pposition strength x (T)ournament status.

I know I'm blowing my own trumpet here a bit but the system has taken a long time to design and develop and has been very much a labour of love for me, coupling my two great loves of Statistics and Tennis

I've always had a love of Statistics and have over 20 years experience within the Government Statistical Service. I can see this same love of data within your posts and I hope we will be able to exchange many posts in the future, both exchanging points of view and helping each other where we can with statistical difficulties and problems.

Take care and keep in touch

Tim

Calvin M.
Dec 11th, 2007, 05:16 PM
I don't believe any rating that puts Seles ahead of Evert, Sabatini ahead of Capriati, Fernandez ahead of Pierce, Jaeger ahead of Austin and so on.

No disrespect to Wuornos (thanks for the compilation) and with the exception of Sabatini over Capriati, I agree with you. MJ Fernandez, for example, had a fine, more consistent career but Pierce is the one who delivered when it counted most.

Wuornos
Dec 11th, 2007, 11:37 PM
No disrespect to Wuornos (thanks for the compilation) and with the exception of Sabatini over Capriati, I agree with you. MJ Fernandez, for example, had a fine, more consistent career but Pierce is the one who delivered when it counted most.

Thanks Calvin

I appreciate all feedback received.

To take the example of Fernandez over Pierce, remember that DOT is not evaluating total career achievement but peak playing standard. You are of course correct in identifying that Pierce won 2 majors while Fernandez didn't win any but DOT looks slightly deeper than that and places equal emphasis on losses as wins. Really DOT is saying there is nothing between them on Peak Playing Standard in that they both score 2674 Peak DOT. E.g. Pierce was 2-4 in major finals while Fernandez was 0-2. Fernandez was 9-8 in major Quarter Finals while Pierce was 6-8. Allowing for the fact that DOT does take into account the excellent point you made about 'when it counted most', this would still leave Pierce slightly ahead.

However, Fernandez outscores Pierce in three important respects.

1. Fernandez achievements were scored within a tighter time frame e.g. 3 major finals finishes, 4 major semi final, and 3 quarter final finishes within the space of 14 consecutive majors. Pierce as you quite rightly identify never managed to produce this consistency, E.g her major wins were 5 years apart.

2. Fernandez had a better record in all but the final round of majors than Pierce and was a more consistent performer making 17 Major Quarter finals to Pierces 14

3. The quality of opposition, Fernandez was scoring her major successes at the height of the rivalry bewtween Graf and Seles, while Pierces main rivals at the time of her peak period were Graf and Sanchez Vicario.

These three factors in favour of Fernandez are just enough to make up the difference of Pierces 2 major wins 5 years apart and 'delivering when it counted most'.

I hope this helps your undersanding of the depth of analysis carried out by DOT.

If you have an further questions or if there is any analysis I can carry out to help convince you of the validity of the DOT ratings, you have only to ask.

Thank you for your interest in my work and your post.

Regards

Tim

Calvin M.
Dec 12th, 2007, 08:52 AM
Thanks Calvin

I appreciate all feedback received.

To take the example of Fernandez over Pierce, remember that DOT is not evaluating total career achievement but peak playing standard. You are of course correct in identifying that Pierce won 2 majors while Fernandez didn't win any but DOT looks slightly deeper than that and places equal emphasis on losses as wins. Really DOT is saying there is nothing between them on Peak Playing Standard in that they both score 2674 Peak DOT. E.g. Pierce was 2-4 in major finals while Fernandez was 0-2. Fernandez was 9-8 in major Quarter Finals while Pierce was 6-8. Allowing for the fact that DOT does take into account the excellent point you made about 'when it counted most', this would still leave Pierce slightly ahead.

However, Fernandez outscores Pierce in three important respects.

1. Fernandez achievements were scored within a tighter time frame e.g. 3 major finals finishes, 4 major semi final, and 3 quarter final finishes within the space of 14 consecutive majors. Pierce as you quite rightly identify never managed to produce this consistency, E.g her major wins were 5 years apart.

2. Fernandez had a better record in all but the final round of majors than Pierce and was a more consistent performer making 17 Major Quarter finals to Pierces 14

3. The quality of opposition, Fernandez was scoring her major successes at the height of the rivalry bewtween Graf and Seles, while Pierces main rivals at the time of her peak period were Graf and Sanchez Vicario.

These three factors in favour of Fernandez are just enough to make up the difference of Pierces 2 major wins 5 years apart and 'delivering when it counted most'.

I hope this helps your undersanding of the depth of analysis carried out by DOT.

If you have an further questions or if there is any analysis I can carry out to help convince you of the validity of the DOT ratings, you have only to ask.

Thank you for your interest in my work and your post.

Regards

Tim

Thanks for the thorough explanation. Looking at your criteria, I understand exactly why MJ Fernandez is ahead of Pierce. The Dominican-American was, without queston, the more consistent performer. My only bone of contenton is that Pierce was in the final of 3 different majors compared to MJ Fernandez's 2, Pierce def. Graf (twice) and if memory serves, MJ Fernandez has no wins against Graf (my aplogies in advance if I'm wrong). MJ Fernandez's attempt at Grand Slam glory was definitely thwarted by the Graf-Seles stranglehold but Pierce's own run to the finals of the majors included wins over Graf, Seles, Hingis, Davenport and Henin.

Wuornos
Dec 13th, 2007, 03:53 PM
Following several postings querying the DOT Rating of Winnie Shaw in comparison with Sue Barker, I promised to look again at the coding for DOT and to check for errors. In doing this I examined those areas which coup possibly effect one but not the other.

I have found an error in the coding that is used to derive a cautious estmate of player rating from limited levels of data. I have now corrected this error but it has impacted on other players as well as Winnie Shaw. As DOT only uses Open Era data in it's evaluations, this has impacted in the main on those players who DOT had perviously estimate their peak performance level as falling during the first four years of the Open Era. Some of these players still have their peak at the time DOT previously identified and for these the correction of the error has had the largest impact. For others the peak has moved to period later and for these players there has only been a partial effect of the overall deflation.

I have corrected the list at post #2.

Thanks to all who have helped in identifying this problem with DOT.

Take care and keep the posts and queries coming.

Regards

Tim