SAS Exam preparation

[Siuli]

Hi,

Please let me know how to derive the AOC equation below:

AOC=percent concordant plus (.5 * percent tied)

Thanks,

Siuli

[Reeza]

You would have to pull the numbers from the ctable and do the calculation in a data step I suspect. How is percent tied derived?

[Siuli]

% tied should be the number of event cases where the predicted probability is same with number of non event cases.

I wanted to know the logic of AOC calculation, how the relation with concordant and 0.5 times of tied is established, so wanted to understand the theoretical logic behind this equation.

[Reeza]

Oh...I assumed this was Area Over the Curve and related to logistic regression. I see that it's not related to regression with SAS so I have no idea about the theory behind that.
Hopefully someone else can help you but you may have more luck on cross validated.

[Siuli]

Yes, this is Area under the curve and part of logistic regression. In SAS website (in the tutorial for SAS Statistical Business Analysis Using SAS 9: Regression and
Modeling), I found the relation as AOC=%concordant + .5%tied. I wanted to know how to derive this equation theoretically. 

If someone can help me would be appreciated.

Thanks,

Siuli

[Reeza]

Area under the curve an area over the curve are different measures...AUC is incredibly common and well documented. I don't see very much about AOC though. Which one are you interested in?

[Siuli · Accepted solution]

Hi,

It was a typo. I am very sorry for the confusion. I want to know how to derive the below equation for Area under the curve (AUC):

Area under the curve (AUC): percent concordant + (0.5 * percent tied)

Please find the attached doc on SAS sample question and refer to Question 10.

Thanks,

Siuli

[Reeza]

It's based on the trapezoid rule for area under the ROC curve. 

https://documentation.sas.com/?docsetId=statug&docsetVersion=15.1&docsetTarget=statug_logistic_detai...

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@Siuli wrote:

Hi,

It was a typo. I am very sorry for the confusion. I want to know how to derive the below equation for Area under the curve (AUC):

Area under the curve (AUC): percent concordant + (0.5 * percent tied)

Please find the attached doc on SAS sample question and refer to Question 10.

Thanks,

Siuli

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[Reeza]

FYI - those questions are problematic in many respects and don't reflect the new style of the tests.