I'm stuck on a conference call. I think I'll run some more plot graphs like these. I'll start with Portland.
Try having a conversation without getting all upset and bitchy. This doesn't make sense. You started this thread claiming there is a correlation between per and usg. Now you are saying the "correlation argument" is ridiculous? Your link didn't provide any correlation or regression data that I could find. The hundreds of plots don't really tell much of a story, imo. If somebody already pulled the data to find the correlation and regression statistics for PER and USG, then what is this conversation about?
It's like asking what the difference between an apple and an orange is. They're just different. A scorer gets a higher PER than a player who does the same things except scores less. A rebounder gets a higher PER than a player who does the same things except rebounds less. These are true statements but are truisms. I think that your questioning of PER is absolutely fair. It can compare apples and oranges to a certain extent, but whether someone likes apples or oranges better is not a question that it can answer. Ed O.
Now hold on a minute. I've got some posters telling me that Usg and PER and too similar, and now you're telling me that they're too dissimilar? Neither of those really matter, though, if you control your equation and then try to derive information from the answers.
About what those results mean and how they could be used to evaluate players. Isn't that obvious? That's the entire point of the thread.
Fair enough. But you haven't shown any results from a significant set of data. That is why I was asking for the correlation and regression data, not just a bunch of plots broken out on a per-team basis, or a few samples from players you selected. People have been saying that per and usg are built on many of the same variables. It shouldn't be a huge surprise that they have some correlation. If you're curious about the strength of the correlation, just pull the data and tell us what it is. Do you know how to do that?
I'm not claiming that I have an extensive data set that I have studied. I am pointing out an observation that I made regarding Usg/PEr, and if meaning can be derived from it. Also, why would I offer an extensive data set for review here? The primary critic in this thread didn't even know what Usage Rate measured, yet I'm supposed to offer up a data set that would literally take days to plot for a critical review. LOL Speaking of being bitchy...
Actually, shouldn't those who criticize using these two parameters in their own equation, solely on the basis of 'correlation', actually offer up the data? Minstrel and andalusian both missed the mark badly when they were speculating on the connection. I wasn't the one claiming "correlation", remember?
Well, you started the thread to discuss a "consistent correlation". I would think you might want to offer data to back it up since you claim to be a stat geek. I don't know why it would take "literally days" to create a scatter plot with PER on the y-axis, usg on the x-axis and various regression fits to that data. That is a pretty simple task for somebody that is interested. Don't get all upset. It was an honest question. If you don't know how to write a script to automatically scrape the data from online sources, I was going to offer to help. Sheesh!
Guys, anyone that wants a good usage-efficiency barometer should also look at this: http://www.basketball-reference.com/blog/?p=5500 Basically, after adjusting for the 1995 environment this is the tradeoff for offensive rating and usage. For each extra possession a star takes on, they gain .833 points in offensive rating. However it does ignore defense, defensive rebounds, steals, blocks, and such. But if you can combine it with an 82games.com approach, it can give you a damn good idea of how a player is performing. For players before 2002 you could look at defensive rating. I would say that PER is still useful for comparing superstars, taking on extra possessions also has value. Of course so does defense which just as a reminder, don't forget about. A more recent article about this season: http://www.basketball-reference.com/blog/?p=8522
Also just to clarify, in 2010-2011, for each extra possession a role player takes on they get penalized by 1.65 points in offensive rating. According to skill curves. Hopefully that clears things up.
I pulled the data for all players, and eliminated anybody with less than 300 minutes played. The linear regression gives: per = 0.54 * usg + 3.8 The r-squared value is: 0.419 Considering that per and usg share many of the same basic stats, it shouldn't be a big surprise that there is a correlation. But the low r-squared value says that much of the scatter in the per data isn't explained by usg%.
Really? Care to show why you reached that conclusion and actually show the work? USG and PER share many variables, but they measure different things. LOL Batting Average and Slugging Percentage use the same basic stats, yet they also measure very different things. Batting Average and OBP use many of the same statistics. Are you also suggesting that Batting Average and Slugging Percentage have a linear correlation, or that Batting Average and OBP have a linear correlation? Put your work out so it can be analyzed. Also, a correlation isn't a bad thing if it can be used to explain the variance between to data sets. I just don't see how your conclusion fits anything being posted in this thread. In your case, any player could be plugged into a forumla, and a predictable result should occur. That's not the case. Why not share the p-value of your work, and also share all of the data?
OBP and SLG are highly correlated... http://cyrilmorong.com/OPS.htm EDIT: I see you've edited your post to replace OBP with Batting Average in most places.
