SmyslovFan wrote:
Rinkleff is wrong to suggest there is a simple 200 point correlation
You've really got to work on your reading comprehension...
chess.com ratings are deflated against USCF
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Apr 22, 2014
0
#903
Adam, you have changed your original post several times. You are still wrong, even now, when you suggest there is a "consistent 200-300 point" difference.
motty474 wrote:
Comparing the two rating systems is pointless - they are completely different mathematical algorithms that are formulated in such a manner that no meaningful data can be extracted from the comparison. Hence any approximations made of the difference between the two rating systems are going to be invalid and hence no valid conclusion can be made. End of story. Source: statistics degree
1031 posts here and this has proabably been said in one way or another a dozen times. Seems trolls don't understand statistics and pools.
I would agree on this data based on what I personally know. I have friends in real life that do have this point difference and in addition, my blitz rating here is 300 points off my FIDE rating and 500 off my CFC rating. Guys, stop attacking the original poster without support.
Apr 22, 2014
0
#906
Eric, there has been plenty of support. If you have the time, read through the comments in this thread. There's a lot of dross, but there are also a few excellent pieces of statistical analysis. And no, Adam didn't do any of that hard work. (Neither did I, but I recognise it.)
The simple empirical data shows that there is a 200 to 300 point higher correlation between USCF ratings and Chess.com blitz ratings. Why you simply refuse to acknowledge this just because you can't calculate an exact formula for it, is puzzling.
AdamRinkleff wrote:
Furtiveking, I've taken statistics, thanks though. I've taken lots of maths actually. You guys really don't know what you are talking about, which is why I thought I'd try to educate you.
Yes, ratings measure the relative strength of a player against the player pool. No kidding? And when you have the same players, in two different pools, you CAN examine what the average difference is. This is not rocket science guys.
Here is a chart to help you understand:
USCF Chess.com Difference
1800 1500 300
2100 1850 250
1200 1000 200
1500 1275 225
1750 1475 275
1850 1575 275
1400 1175 225
1300 1100 200
2000 1750 250
1900 1600 300
Average Difference: 250
You guys can do this for yourself, if you are smart enough to handle the equations. I think you guys have been so busy believing there isn't any way to compare the rating pools, that you haven't quite considered that this -is- statistics, and there is always a mathematical relationship between any two sets of numbers.
We are talking about comparing chess ratings with chess ratings... lol, that's not apples and oranges, that's chess and chess. Its the same thing. When you have the same people, playing the same game, trust me... there is going to be a mathematical relationship which describes their average ability.
incorrect. I am rated 900 points higher on chess.com than I am in USCF... soo...
My chess.com ratings are in the 1400s-1650s and I am 1360 U.S.C.F....
Sundayfan wrote:
incorrect. I am rated 900 points higher on chess.com than I am in USCF... soo...
Please learn to read and think before you post...
dpnorman wrote:
My chess.com ratings are in the 1400s-1650s and I am 1360 U.S.C.F....
Did you notice how your USCF rating went up 250 points since January...
EricWang2000 wrote:
I would agree on this data based on what I personally know. I have friends in real life that do have this point difference and in addition, my blitz rating here is 300 points off my FIDE rating and 500 off my CFC rating. Guys, stop attacking the original poster without support.
Yah, Smyslov just doesn't get it, but he feels this obsessive need to keep telling everyone and spamming the thread.
AdamRinkleff wrote:
EricWang2000 wrote:
I would agree on this data based on what I personally know. I have friends in real life that do have this point difference and in addition, my blitz rating here is 300 points off my FIDE rating and 500 off my CFC rating. Guys, stop attacking the original poster without support.
Yah, Smyslov just doesn't get it, but he feels this obsessive need to keep telling everyone and spamming the thread.
This issue, while facially about the numbers, seems to emotionally or viscerally "cut a little close" for a lot of people. I have no idea why; but then again, I'm not really much of a serious chess player.
johnmusacha wrote:
Why you simply refuse to acknowledge this just because you can't calculate an exact formula for it, is puzzling.
Its not puzzling. Smyslov is a disagreement troll. His sole objective is to continually tell everyone how wrong I am and act surprised that anyone would agree with me. It doesn't really matter what anyone says, he is just going to repeat the same statements over and over. He has added nothing to this conversation, and isn't likely to do so. He simply wants to spam the thread with negativity and criticism, so that he can derail the conversation and feel satisfied with his ability to "win" an argument.
In his very first post (the second in this thread) he started going on about "online" chess when obviously we aren't talking about that, and making trite statements like "[ratings] measure the population that plays." Its like talking to a computer that is pretending to carry on a conversation. I doubt he really has any clear idea what we are talking about (he certainly didn't read my original post very carefully, nor anything since), and he has just latched onto the idea that we are wrong and therefore we are wrong and so he needs to keep saying that over and over as if we care what he thinks.
@AdamRinkleff
This is true (technically only 150 points since January; 250 points since December), and hopefully the signal that my real rating should be closer to my chess.com ratings. Still, I don't understand those who say U.S.C.F. ratings are universally higher than chess.com ratings. I think that is the case with high ratings, but certainly not low ratings. Perhaps chess.com's ratings are more average/moderate than U.S.C.F.
On a sidenote, how did you know that about my rating? U.S.C.F. rating lookup?
dpnorman wrote:
@AdamRinkleff
1) This is true and hopefully the signal that my real rating should be closer to my chess.com rating.
2) Still, I don't understand those who say U.S.C.F. ratings are universally higher than chess.com ratings.
1) Your USCF rating is going to wind up higher than your chess.com rating, just wait and see. Congratulations, you are a 1600 USCF. A few more tournaments and you'll be there!
2) Nobody said USCF is universally higher, but it averages 2-300 points higher for people who actively play both USCF and chess.com. There are always exceptions.
Apr 22, 2014
0
#917
JCButler did a statistical analysis and came to the conclusion that Adam's figures are wrong. Here's what he wrote:
"Jcbutler wrote:
There appear to be two kinds of people at Chess.com: those who care about their ratings and wonder how well they correspond to “real” ratings like USCF ratings, and those who dismiss the importance of ratings and question how they could possible mean anything at all. Another point of contention has been whether Chess.com ratings are inflated or "deflated" relative to USCF ratings. Fully aware of the risks of entering into a debate that has become heated at times, I humbly offer my own insights below, along with selected summaries from people who have considered this question before.
A couple of years ago, for example, DrawMaster examined data from more than 100 Chess.com members, rated 1500 to 1699, who also reported USCF ratings on their profiles. His main finding was that these members had Chess.com blitz ratings that were, on average, 73 points lower than their reported USCF ratings (1592 vs. 1665). He also provided a graph showing a linear relationship between USCF ratings and Chess.com ratings. He concluded tentatively that online blitz ratings "generally, if only slightly" underestimate OTB playing strength.
AdamRinkleff also argued that Chess.com blitz ratings were generally lower than USCF ratings, but he stated that the discrepancy was quite a bit larger. According to his own observations of about 20 people who maintain active ratings in both systems, AdamRinkleff suggested that Chess.com ratings are consistently 200-300 points lower than USCF ratings. Unfortunately, this claim was put forth from a small sample and without supporting statistical analysis. This led to a substantial debate on the forum and no real consensus. Many posters claimed that the two sets of ratings were like “apples and oranges” and could not be meaningfully compared.
In an attempt to test AdamRinkleff's hypothesis, ShindouHikaru posted data from 54 Chess.com members who had USCF ratings that had been verified by official records. Unlike DrawMaster's data, this sample was well above average in skill level, with many of the players taken from a list of titled players on the website. ShindouHikaru concluded that although many players had lower Chess.com ratings than USCF ratings, there was no formula he could detect for explaining the relationship.
I got interested in the question at this point and decided to do some additional statistical analyses. I took ShindouHikaru's data, which he had kindly posted on the forum, double checked the USCF ratings and adjusted them for changes in the intervening months. I also added additional data to the sample by using my friends, friends of friends, etc. I only included members if they had active, nonprovisional ratings based on many games. I examined blitz ratings, online (correspondence) ratings, tactics ratings, and USCF regular ratings.
Obviously, this is a nonrepresentative, convenience sample and I would have preferred a large, random sample of chess players from both systems. Nevertheless, the data are still useful and allow us to answer some questions about how the variables relate to each other. In the end, I was able to gather data from 80 people, which I figured would be large enough to detect statistically significant effects. If any Chess.com staff are reading this and curious about these findings, I could do a much more extensive analysis with access to more data...
According to my results, the average Chess.com blitz rating for this sample was 1817 and the average USCF rating was 1945. This supports previous statements that Chess.com ratings tend to be lower than USCF ratings. The difference was 128, which is higher than DrawMaster’s estimate, but lower than AdamRinkleff's. All the variables in the analysis were highly correlated with each other, suggesting that they are all aspects of the same underlying entity of chess skill. USCF ratings correlated r = .83 with tactics ratings, r = .79 with online ratings, and r = .93 with blitz ratings, all p < .001.
Blitz ratings are strongly related to USCF ratings in these data. Honestly, I was shocked at the magnitude of the correlation. Rather than apples and oranges, the situation is more like apples and apples of the same variety, but from a different tree. Then again, the fact that the sample consisted of active, relatively high level players who were serious enough about their Chess.com ratings to put their names on their profiles may have influenced the results. I would expect the correlation to go down with a larger, more casual sample of players.
Because the ratings are so closely related, it makes sense to use regression to calculate an equation to predict one from the other. This produced the following formula: USCF estimate = (Chess.com rating * .93) + 283. Or, if you don’t like math, you could do almost as well with the simpler formula where you just add the difference: USCF estimate = Chess.com rating + 128. Remember these are just estimates based on generalizations. Your mileage may vary.
As a final note, I was perusing the discussion on this issue in the forums and found a post by Pegrin from several years ago. Using Google, he found 59 Chess.com profiles that contained USCF ratings. With the caveat that people’s self-reported ratings might not be accurate, he computed a Pearson correlation of r = .67 and a regression equation of USCF estimate = (Chess.com rating * .74) + 280.5. My data suggest that this would underestimate the USCF rating for serious chess players, but I’ll leave it to the reader to decide which formula works best for them.
So what's my conclusion, for those of you who just skipped to the bottom? According to all the available data, Chess.com ratings and USCF ratings are substantially and meaningfully related to each other. They are clearly the same type of fruit. Also, people generally have lower Chess.com ratings than their published USCF ratings. Finally, the pattern in the data is clear enough that you can get a quick and reasonably accurate estimate of your USCF rating from your Chess.com blitz rating. You can try one of the formulas above, of if you are math phobic, just draw a regression line over the scatterplot with your finger and see where your USCF rating should be."
SmyslovFan wrote:
USCF estimate = (Chess.com rating * .93) + 283.
More spam from Smyslov, who feels compelled to wall of text this thread...
Really though, Butler said I was wrong? Of course, he didn't say that, but it sounds good right? I'm pretty sure if you read carefully, you'll find where he said, "This supports previous statements that Chess.com ratings tend to be lower than USCF ratings... Chess.com ratings and USCF ratings are substantially and meaningfully related to each other. "
Besides, USCF = chess.com + 200 is really not very different from USCF = chess.com (0.93) + 283.
If you want to nitpick over the difference (which you are, to an annoying extent), jcbutler used a less rigorous definition of what an "active" player is. Individuals who haven't played a lot of games are more likely to be either overrated or underrated.
Apr 22, 2014
0
#919
AdamRinkleff wrote:
SmyslovFan wrote:
USCF estimate = (Chess.com rating * .93) + 283.
More spam from Smyslov, who feels compelled to wall of text this thread...
Really though, Butler said I was wrong? Of course, he didn't say that, but it sounds good right? I'm pretty sure if you read carefully, you'll find where he said, "This supports previous statements that Chess.com ratings tend to be lower than USCF ratings... Chess.com ratings and USCF ratings are substantially and meaningfully related to each other. "
Besides, USCF = chess.com + 250 is really not very different from USCF = chess.com (0.93) + 283.
Just saving this in case he goes back and retro-edits yet another post.
Others can read what they each said and come to their own conclusions.
motty474 wrote:
Comparing the two rating systems is pointless - they are completely different mathematical algorithms that are formulated in such a manner that no meaningful data can be extracted from the comparison. Hence any approximations made of the difference between the two rating systems are going to be invalid and hence no valid conclusion can be made. End of story. Source: statistics degree
This is completely erroneous.
There are two main reasons there is not a nice 1-to-1 ratio between FIDE, USCF and online sources:
The populations are not the same. The distribution will be close to normal (a statistical term), but they measure different populations so individuals in one population will be in a different part of that distribution in another population.
USCF and FIDE rate different events than chess.com does. Players at chess.com often play casually, at 1am local time. They play after having a few drinks or a large meal. Competitive OTB players usually treat their events, which they pay for, more seriously. They tend to play more slowly, too.
AdamRinkleff wasn't even comparing the same time controls and came up with a one-size fits all comparison that has been proven to be completely unfounded.
People with real statistics backgrounds have shown that there are some correlations that can be made between the two populations and ratings, but it fits a range, not simply adding or subtracting a number.
From a statistical perspective, this is not comparing apples to oranges, this is comparing apples in one orchard to apples in another orchard. This is not suggesting that Tennis federation ratings can be used to predict chess ratings. This is comparing different populations of chess players who play at different time controls and in different contexts. There are many similarities, but the differences are also critical.
Many people on this thread seem to be swayed by extremist arguments without considering the actual data. Rinkleff is wrong to suggest there is a simple 200 point correlation, as are people who argue that any comparison is impossible.