RPI/SOS Question

[MarsupialMadness]

How much does teams we play beating other great teams help us with RPI?  I understand it to a degree, but I'm wondering how big or how drastic the sway is in either direction.

For instance, us beating Wisconsin and Wisconsin beating Indiana obviously helps us, but how big of a factor is it in the end?  If Wisconsin had lost that game, does it significantly effect where our RPI ends up?  Wisconsin beating Indiana boosts Wisconsin's rank, so in the end are we getting double points because we beat a top (x) RPI team and because Wisconsin beat Indiana?  I may have confused that up a bit.

If Butler beats Gonzaga tonight, is it a big deal for us?  Enough to get excited about?  Does it matter that to us that Butler is winning against top ranked teams and they barely beat us?

My general rule that is that I always root for the non-conference teams that we have played to win.  They better they get, the better we look.  But I guess I can't really explain why that is, so if anyone out there with better knowledge could break it down, I would appreciate it.

[ChicosBailBonds]

http://www.rpiforecast.com/teams/Marquette.html


Scroll down to the part that talks about contributions of individual teams. 

[MarsupialMadness]

Good information, thanks.

[The Equalizer]

How much does teams we play beating other great teams help us with RPI?  I understand it to a degree, but I'm wondering how big or how drastic the sway is in either direction.

For instance, us beating Wisconsin and Wisconsin beating Indiana obviously helps us, but how big of a factor is it in the end?  If Wisconsin had lost that game, does it significantly effect where our RPI ends up?  Wisconsin beating Indiana boosts Wisconsin's rank, so in the end are we getting double points because we beat a top (x) RPI team and because Wisconsin beat Indiana?  I may have confused that up a bit.

If Butler beats Gonzaga tonight, is it a big deal for us?  Enough to get excited about?  Does it matter that to us that Butler is winning against top ranked teams and they barely beat us?

My general rule that is that I always root for the non-conference teams that we have played to win.  They better they get, the better we look.  But I guess I can't really explain why that is, so if anyone out there with better knowledge could break it down, I would appreciate it.

First, remember that the RPI is 3 components
Component 1 (weighted at 25%)  Your own W/L
Component 2 (wegithed at 50%):  Your opponents' average W/L
Component 3 (weighted at 25%): Your opponents' opponents' average W/L

We have ~32 opponents.
Each one of them has ~32 opponents.

So any individual game by any individual opponent of ours impacts 1/32 x 1/32, or 1/1024th of Component 2 of our RPI.  1/1024 = .000977.  But since Component 2 is weighted at 50%, its actually .000488.

As an aside, because a win by an opponent results a loss to one of their opponents, it impacts our Component 3 slightly--but the weighting is less--1/32 of 1/32nd of 1/32nd of 25% of our RPI.

Next, keep in mind that RPI is not a rank (like 32nd).  Its a 4-digit decimal (e.g. .6239).

The impact on Component 2 of any one game to us is worth about.000488 to that 4-digit decimal for a win, or -.000488 for a loss.  

One of the things people get confused over is they think the quality of our opponents wins has an impact on our RPI.  In reality, Butler's win over Indiana is worth to us exactly the same as their win over New Orleans or IUPUI.  In other words--to specifically address your question, it does not matter one bit that Butler is winning against top ranked teams and they barely beat us.  Every win help, every loss hurts, and we don't care who those wins or losses came against.

Finally, there is a slight impact on Componet 3--let's say IU is 25 wins better than IUPUI--each of those 25 wins is worth an improvement of .0000076 to our RPI.  (25% x 1/32 x 1/32 x 1/32).  But we get most of the value of Indiana by vritue of Butler playing them--


 

[MarsupialMadness]

That cleared up a lot, thanks for the breakdown.