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Look at the next 5 teams down the list. In the last game they played, the depleted Blazers beat 4 of them. (We could have beat Orlando too.)

I was worried that we played too many patsies early on and that it would catch up to us. But somehow we are doing even better now against contenders. Go Blazers!

over 2 years ago Cap004_tiny LaoTzu 7 comments 0 recs  | 

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This is the problem with Hollinger

Especially with things like the playoff predictor. He manufactures these statistics, but never even attempts to provide any sort of confidence interval or error estimate. They may be unbiased estimators, in that the average deviation from the actual for a given trial is 0, but that doesn’t mean there are errors associated. Only in sports could someone pretend to make predictions without giving some sort of description of the associated error.
These same problems also apply to the supposed “Predictions” of PER by Hollinger. I would be shocked if the average deviation between actual and predicted is any better than just predicting repeats of last years performance.
People who make statistical predictions should be under the burden of showing some sort of validity. Otherwise they are just using a fraudulent appeal to science in order to lend their arguments credence.

by jnewhouse on Dec 26, 2009 11:14 AM PST reply actions  

Hollinger has said many times that his stat predictions are not an end all be all of anything and are based only on statistical information.

So with that said take it as you will. And with that said, Hollinger’s stats and predictions are more accurate than people give him credit for.

by Bskey on Dec 26, 2009 12:34 PM PST up reply actions   1 recs

True Dat

He tries with the very limited amount of statistics available to make something better than before…. Not perfect mind you, but better, and he does a very good job at it.

Joel Freeland=Stud

by hightide on Dec 26, 2009 1:15 PM PST up reply actions  

Um, why do you think he has playoff "probabilities"?

What more do you want? It’s a simple Monte Carlo simulation, he gives the maximum and minimum values for the variations, and orders them based on the most likely outcome of the simulation. Notice how the probabilities show his system is much more confident that the Lakers will make the playoffs than the Spurs. Calling that not any kind of “confidence interval” is just needless nitpicking.

#52

by Royster on Dec 27, 2009 10:42 AM PST up reply actions  

Because the probabilities aren't actually exact, and to say that the blazers

have a 94.8% chance to make the playoffs with no margin of error is not correct. The basic premise that hollinger works off of is that the strength of each team can be quantified by a single number, or rating, and that the probability that a given team will win a single game is determined by the ratings of the two teams.
 In other words, for any two rankings, the scoring margins and other statistics should have a distribution. i.e. if one team is much better than the other, then we would expect the distribution to favor blowouts by the better team more than say close games. If the two teams were equal, we would expect a symmetric distribution. The simplest way to model this in basketball terms would be with a normal distribution around the expected margin, and a standard deviation based on historical data.
There is no problem with this theory. In fact, I rather like it. However, what Hollinger, and anyone else, must try to do is get estimates on what a teams “true” rating is based on the observed results of a limited number of trials, the games. As such there is an associated error between the best estimate of the rating and the actual value. For a simple example, think of polling. This is an attempt to determine the true percentage of voters on either side of an issue or candidate by taking a limited number of samples. Such polls are ALWAYS accompanied by margins of error (which is the inherent mathematical error, and doesn’t account for sampling errors, question bias or other methodological errors). In polling, and most other disciplines, prognosticators are obligated to provide some idea of how accurate their estimations are.

The problem with the playoff predictor is that it presumes that the Hollinger Rankings accurately reflect teams relative strengths, and thus give an effective prediction of the likelihood that, say, the Blazers beat the Sixers tonight. If the probabilities could truly be calculated, then the playoff predictor would be accurate and no confidence interval would be necessary. However, we don’t know exactly how likely it is that the Blazers beat the Sixers, although we could, using past data, probably show that it is likely better than 50%. However, any calculations based on this percentage would also be accompanied by some variance, which should be calculated and shared.

The idea of an error on a likelihood is a little unintuative, and it might help to think of it in terms of polling again. The percentages given, such as 53% for Obama, are really the likelihood that any one person will vote for obama. However, we don’t know that this is really the right precentage, so we include a 95% confidence interval of +/-5%, to give an idea of how accurate this prediction should be. There is a difference between polling 2000 people to get 50% with a +/-2% and 20 people to get 50% with a +/-20%. The second poll wouldn’t be given too much credence. I think that any honest calculation of variance for Hollinger’s playoff odds would look more like the 20 person sample. This is not a knock on his mathematical or statistical abilities, simply that the game of basketball is highly variable and should reflect that.

by jnewhouse on Dec 28, 2009 9:54 AM PST up reply actions  

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