Paper, pencil, brain ;-) [Software]

posted by Helmut Homepage – Vienna, Austria, 2009-09-21 20:33 (5302 d 12:25 ago) – Posting: # 4226
Views: 24,883

Dear Yuvraj!

❝ Suppose Geometric Least Square Mean Ratio (T/R)=1.20

❝ Lower Confidence Limit=1.08

❝ Upper Confidence Limit=1.33

❝ Number of Subjects (N)=42

❝ Degrees of Freedom=N-2=40;

❝ TINV(.10,40)=1.683851


So far, so good.

❝ Based on Lower Confidence Limit

CVintra=100*SQRT(EXP(MSresidual)-1)=26%

❝ Based on Upper Confidence Limit

CVintra=100*SQRT(EXP(MSresidual)-1)=29%


I can’t follow you. Which formula were you using? :confused:
I got:
MSE based on lower CI and PE: 0.0430666 (CV 21.0%)
MSE based on upper CI and PE: 0.0410446 (CV 20.5%)

Recalculating the CI from the estimated MSEs and the reported PE of 1.20 I got
CI based on lower: 1.06 – 1.36, and
CI based on upper: 1.07 – 1.35,
which is pretty close to the original 1.08 – 1.33…

The actual CVintra in the study likely was <20.5%, since the reported CI was tighter than both estimates. This discrepancy is due to the limited significant digits of the reported CI and PE. However, since the estimate is conservative you are on the safe side.

❝ I want to confirm,

❝ Whether I am right or wrong?


Probably wrong.

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