tag:blogger.com,1999:blog-3299311926633621468.post4046977418191414328..comments2024-05-29T00:46:59.821-07:00Comments on Objective NHL: Even Strength Outshooting and Team QualityJLikenshttp://www.blogger.com/profile/02570453428274983835noreply@blogger.comBlogger13125tag:blogger.com,1999:blog-3299311926633621468.post-57609107751850392972013-05-03T13:16:41.028-07:002013-05-03T13:16:41.028-07:00Team quality is something so vague. because they a...Team quality is something so vague. because they aren't constant so you can say that have quality. Hostpph.comhttp://www.hostpph.comnoreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-46563560787036579352011-01-30T09:08:02.620-08:002011-01-30T09:08:02.620-08:00Thanks JLikens! I suppose I was curious about the...Thanks JLikens! I suppose I was curious about the "close" data because we're often trying to analyze small samples of games (near the beginning of a season, a playoff series), and it would be interesting to know if using the "close" data generally yields similar results over the long haul, since particularly in those smaller samples of games, it's nice to have the extra events.Scott Reynoldshttps://www.blogger.com/profile/05735545121522530577noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-7958210406393300502011-01-29T16:49:08.920-08:002011-01-29T16:49:08.920-08:00And to answer your second question, I didn't r...And to answer your second question, I didn't repeat the analysis with EV tied, but I suspect the correlations would be slightly lower, given that score effects are still relevant when the score margin is one in the first two periods. <br /><br />Though on the other hand, EV score close does provide a more adequate sample.JLikenshttps://www.blogger.com/profile/02570453428274983835noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-28379447157689185692011-01-29T14:40:03.860-08:002011-01-29T14:40:03.860-08:00Thanks Scott.
I use % of variance in goal ratio a...Thanks Scott.<br /><br />I use % of variance in goal ratio attributable to luck as a proxy for the level of parity in the league, but looking at the team-to-team spread in goal differential would accomplish the same thing (at least for recent years, where the scoring context hasn't changed that much). <br /><br />The comment itself was basically just an offhand remark on my part. Thinking about it more carefully, the correlation between the two variables would depend less on the level of parity in the league and more on the structure of the data. <br /><br />For example, there was relatively little parity in the league in 2003-04. But the correlation between EV Tied shot ratio and goal ratio was high because the teams that did well with the former tended to also do better with the percentages. <br /><br />The level of parity in 2006-07 was about the same as in 2003-04. However, unlike in 2003-04, there was a negative correlation between the percentages and EV outshooting with the score tied. Consequently, the correlation between EV tied shot ratio and goal ratio was much lower.JLikenshttps://www.blogger.com/profile/02570453428274983835noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-89518971285898138142011-01-28T14:21:50.803-08:002011-01-28T14:21:50.803-08:00Great post JLikens.
I was curious about how you...Great post JLikens. <br /><br />I was curious about how you decided that there was more parity in the league over the last three seasons, and how that might impact the value of EV shot differential. I took a brief look at the goal differentials since the lockout and added them up as absolute values for each season, which gave me the following results:<br /><br />2005-06: 1076<br />2006-07: 1168<br />2007-08: 650<br />2008-09: 870<br />2009-10: 834<br /><br />That rather simple method suggests that your assertion is correct in that the first two years had a lot more variance from zero than the last three; however, the third season is quite different from the last two, and yet we don't see that result in EV shot differential contributing more to winning in that third year. I found that a bit odd given your hypothesis and was wondering if you could comment. Perhaps you're calculating level of parity differently and the third year is more similar to the last two? Or maybe it's just a shit happens thing...<br /><br />In addition, I was curious if you did a similar exercise with "EV Close" data, and if so, how much different it was from "EV Tied".Scott Reynoldshttps://www.blogger.com/profile/05735545121522530577noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-31478127536410795942011-01-27T18:34:11.121-08:002011-01-27T18:34:11.121-08:00Random selection without replacement.
And in rela...Random selection without replacement.<br /><br />And in relation to your other post, you make an interesting point about the relationship between the percentages and outshooting. <br /><br />Prior to the 2006-07 season, when there was less parity in the league, outshooting teams tended to do slightly better in terms of the percentages. Since then, however, the reverse has been true.<br /><br />You suggest that the negative relationship between outshooting and shooting percentage is "built in", which seems sensible enough. <br /><br />It could very well be that,in today's salary cap world, players that can finish are more or less uniformly distributed throughout the league, which allows the above relationship to manifest. <br /><br />But prior to the lockout, it seemed as though the outshooting teams tended to have more players that could finish, which may have masked the relationship between outshooting and the percentages.<br /><br />I'm not saying that's the answer - just offering it up as a possibility.JLikenshttps://www.blogger.com/profile/02570453428274983835noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-62795332831325408352011-01-27T17:02:09.585-08:002011-01-27T17:02:09.585-08:00On the second method, were you using true quarter ...On the second method, were you using true quarter seasons (i.e. 20 consecutive games) or a random selection of 20 games without replacement?Vic Ferrarihttps://www.blogger.com/profile/16425585921916867277noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-52613824268060097932011-01-27T16:36:54.834-08:002011-01-27T16:36:54.834-08:00Nice to see your comments again, Vic.
The formula...Nice to see your comments again, Vic.<br /><br />The formula is actually empirically derived. Using one randomly selected quarter of the schedule as one data set, and another randomly selected quarter as the other, I determined the average correlation between the two data sets for each variable. <br /><br />I then repeated the exercise through using half of the schedule as my data set. <br /><br />I found that the formula was able to predict, with reasonable accuracy, the "half-schedule" reliability, through using the "quarter-schedule" reliability as the input value.<br /><br />Then it occurred to me that there ought to be another way to estimate the seasonal reliability co-efficients - specifically, if you know the half-sample variance, the half-sample reliability, and the full-sample variance, then you ought to be able to determine the full-sample reliability on the basis that the variance due to luck should halve if the sample size was doubled.<br /><br />I decided to see if this second method could correctly predict the half-sample reliability values from the quarter sample reliability values. Unfortunately, I found that it tended to overestimate the actual values by 0.03-0.05. <br /><br />I never figured out what the problem was, so I decided to use the first method.JLikenshttps://www.blogger.com/profile/02570453428274983835noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-21926259206540954912011-01-27T12:17:38.652-08:002011-01-27T12:17:38.652-08:00In the post above that should read:
They also wil...In the post above that should read:<br /><br /><i>They also will try to make plays at the blue lines that other guys just <b>don't</b>.</i>Vic Ferrarihttps://www.blogger.com/profile/16425585921916867277noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-49786872906692668722011-01-27T12:15:57.071-08:002011-01-27T12:15:57.071-08:00Thinking about it a bit more, just food for though...Thinking about it a bit more, just food for thought:<br /><br />With a lot of players, they take chances that sacrifice territorial advantage (outshooting). But it makes sense for them, because they can finish. They cheat for offense, cherrypick, create stretch pass opportunities ... call it what you like. They also will try to make plays at the blue lines that other guys just do.<br /><br />Think Pavel Bure. Or in our era Heatley or Kovalchuk at the high end, Lupul or Ribeiro at the low side. <br /><br />i.e. there is a negative covariance between outshooting and shooting% built in. And because it's generally weaker teams signing the one-dimensional star players, I don't like our chances of prising this information out of the population.Vic Ferrarihttps://www.blogger.com/profile/16425585921916867277noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-54270360645070370002011-01-27T11:18:19.245-08:002011-01-27T11:18:19.245-08:00Terrific stuff as always JLikens, you're on fi...Terrific stuff as always JLikens, you're on fire lately.<br /><br />Not that I disagree entirely, but where does this:<br />reliability = 1- [(1- split half reliability)/SQRT(2)]<br />come from, J?Vic Ferrarihttps://www.blogger.com/profile/16425585921916867277noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-11725930644163124522011-01-27T11:04:39.052-08:002011-01-27T11:04:39.052-08:00Thanks.
I used EV shots rather than Fenwick or Co...Thanks.<br /><br />I used EV shots rather than Fenwick or Corsi for the sake of consistency (I don't have data on EV missed or blocked shots from 2005-07).JLikenshttps://www.blogger.com/profile/02570453428274983835noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-51876558152304999952011-01-27T07:59:13.398-08:002011-01-27T07:59:13.398-08:00Great post and another feather in the cap of the &...Great post and another feather in the cap of the "outshooting theory". <br /><br />Just a quick question, when you talk about EV Shot Ratio are you referring to just shots, Corsi or Fenwick?Ryan Popilchakhttp://sports-opinionated.comnoreply@blogger.com