MGR
★    

India,
2015-11-13 08:43
(3080 d 14:43 ago)

Posting: # 15634
Views: 6,567
 

 Inter CV calculation for parallel study [Power / Sample Size]

Hi all,

How to calculate Inter CV of a parallel study from the values of Confidence interval, Ratio and N?

For Example:

CI lower = 0.876
CI Upper = 1.02
Ratio = 0.96
N = 122

The above results are from a Parallel study.

Please suggest how to calculate the Inter CV from the above data.

Thanks in advance,

Regards,
MGR
d_labes
★★★

Berlin, Germany,
2015-11-13 12:13
(3080 d 11:13 ago)

@ MGR
Posting: # 15635
Views: 5,223
 

 Total CV for parallel study from CI

Dear MGR,

it is only possible to get the total (inter+intra) CV from a parallel group study.

With this in mind and assuming 90% CI you can do in the software R :cool::
library(PowerTOST)
CVfromCI(lower=0.876, upper=1.02, n=122, design="parallel")

gives you a CV = 0.258 (25.8%).

If you don't have R you can do the algebra behind by hand. It's not so hard. See Helmut's lectures about "sample size estimation". Change degrees of freedom and design constant according to the parallel group design.

Better install R, it's free. And use the "gold standard" package PowerTOST :-D.

Regards,

Detlew
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