SRS Formula Changed on basketball-reference?

sp6r=underrated · Post #1 » by **sp6r=underrated** » Sun Mar 18, 2012 3:04 am

When comparing teams across eras, I've always felt the beginning point of any comparison is looking at how they did against their respective peers. I've always like the SRS formula on b-r because it gives a quick shot of the most important metric for evaluating teams MOV with a SOS adjustment. I noticed today that the results are slightly different than I remember.

Here is a blog post from b-r that has the SRS of top teams from 2007 that was written in 2008.

Team Margin SOS SRS

San Antonio Spurs 8.35
Dallas Mavericks 7.28
Phoenix Suns 7.27
Houston Rockets 5.04
Chicago Bulls 4.52

http://www.basketball-reference.com/blog/?p=39

According to their team page today this is their SRS:

San Antonio Spurs 8.11
Dallas Mavericks 6.19
Phoenix Suns 7.32
Houston Rockets 4.46
Chicago Bulls 4.14

Does anyone know why the results are different? How did they change the formula?

My guess is that it looks like they included PS play but I'm not sure.

Thanks

ElGee · Post #2 » by **ElGee** » Sun Mar 18, 2012 5:22 am

Your guess is correct. For some reason, the seasonal summary of "advanced" stats now includes an SRS adjusted for the PS. I say "for some reason" because the rest of the stats are for the RS, so it's a slightly mislabeled stat as of now.

Frankly, I think it's pretty cool to have SRS include the playoffs, but it should be noted as such since it's atypical to combine RS and PS numbers in basically ANY other stat in basketball (and on their site).

sp6r=underrated · Post #3 » by **sp6r=underrated** » Sun Mar 18, 2012 6:34 am

ElGee wrote:Your guess is correct. For some reason, the seasonal summary of "advanced" stats now includes an SRS adjusted for the PS. I say "for some reason" because the rest of the stats are for the RS, so it's a slightly mislabeled stat as of now.

Frankly, I think it's pretty cool to have SRS include the playoffs, but it should be noted as such since it's atypical to combine RS and PS numbers in basically ANY other stat in basketball (and on their site).

Thanks. I was pretty sure that was the change when I looked at the 01 lakers who had the biggest MOV jump from RS to PS that I know of in NBA history and sure enough there SRS was over two points higher.

Like you I like the change but it should be noted because if you hadn't have seen the old # you would assume it was just RS

sp6r=underrated · Post #4 » by **sp6r=underrated** » Sat Mar 31, 2012 4:19 am

ElGee wrote:Your guess is correct. For some reason, the seasonal summary of "advanced" stats now includes an SRS adjusted for the PS. I say "for some reason" because the rest of the stats are for the RS, so it's a slightly mislabeled stat as of now.

Frankly, I think it's pretty cool to have SRS include the playoffs, but it should be noted as such since it's atypical to combine RS and PS numbers in basically ANY other stat in basketball (and on their site).

They changed it back to RS only. Very strange.

mysticbb · Post #5 » by **mysticbb** » Sat Mar 31, 2012 8:57 am

sp6r=underrated wrote:They changed it back to RS only. Very strange.

I don't think they wanted to change it in the first place. SRS is based on OLS and I guess they accidentally included all playoff games in the regression instead of only the regular season games. They may just have fixed that error now.

ronnymac2 · Post #6 » by **ronnymac2** » Mon Apr 9, 2012 4:25 pm

sp6r=underrated wrote:
ElGee wrote:Your guess is correct. For some reason, the seasonal summary of "advanced" stats now includes an SRS adjusted for the PS. I say "for some reason" because the rest of the stats are for the RS, so it's a slightly mislabeled stat as of now.

Frankly, I think it's pretty cool to have SRS include the playoffs, but it should be noted as such since it's atypical to combine RS and PS numbers in basically ANY other stat in basketball (and on their site).

They changed it back to RS only. Very strange.

Good, because having it the other way is incredibly annoying.