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Back to the forum  2018-07-20 11:03 CEST (UTC+2h)
sudy
Junior

India,
2017-08-01 13:29
(edited by sudy on 2017-08-01 13:49)

Posting: # 17641
Views: 1,710
 

 Inter subject CV calculation [General Sta­tis­tics]

Hi all,
Can anyone suggest any logic on below results?

[image]


Why Inter subject CV is not calculated for Cmax?
Is this formula is correct to calculate between subject variability on log transformed data for two way cross over study?
If i calculate manually in excel, I am getting the value around 28% for cmax. But SAS gives error.
One more point i have noted that, the MSS is very low by SAS, but manually this value is very high.
Why R-square is very low for Cmax?


Edit: Category changed; see also this post #1. [Helmut]
Helmut
Hero
avatar
Homepage
Vienna, Austria,
2017-08-01 14:33

@ sudy
Posting: # 17642
Views: 1,459
 

 √x, where x<0

Hi sudy,

next time you upload a PNG please 640px (longest side) or better only the numbers. I had a hard time to read the results. :cool:

» Why Inter subject CV is not calculated for Cmax?

Unless you want to deal with imaginary numbers, the square root of a negative value is not defined. Since ℯ(MSs – MSe)/2 = 0.994155, √–0.005845 don’t work.

» Is this formula is correct to calculate between subject variability on log transformed data for two way cross over study?

Yes. See there.

» If i calculate manually in excel, I am getting the value around 28% for cmax. But SAS gives error.

Please check what you have done in Excel. Cannot work:

A1 0.06596695
B1 0.07769188
C1 =(A1-B1)/2
D1 =EXP(C1)
E1 =D1-1
F1 =100*SQRT(E1)

What do you get? 28% is CVintra – in Excel-lingo 100*SQRT((EXP(B1)-1)).

» One more point i have noted that, the MSS is very low by SAS, but manually this value is very high.

No idea. I don’t have a crystal ball which could tell me what you are doing “manually”.

» Why R-square is very low for Cmax?

Higher variability than the ones of AUCs ⇒ lower R2. As expected.

Cheers,
Helmut Schütz
[image]

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