Sridhar.E
☆

India,
2021-04-27 16:49
(1236 d 06:57 ago)

Posting: # 22331
Views: 2,844

## inter subject CV to intra subject CV [Power / Sample Size]

Hai all,

can any one help how i convert inter subject CV to intra subject CV for sample size estimation.

regards.,

Sridhar

Helmut
★★★

Vienna, Austria,
2021-04-27 17:14
(1236 d 06:32 ago)

@ Sridhar.E
Posting: # 22332
Views: 2,456

## No relationship between CVinter and CVintra

Hi Sridhar,

❝ can any one help how i convert inter subject CV to intra subject CV for sample size estimation.

What do you mean by ‘convert’? It’s like saying ‘convert an apple to an orange’. Both are approximately spherical fruit, more or less sweet and of similar weight. However, they are exclusively distinct.

If you have a crossover study, both CVs are accessible. If you have a parallel design, you get only the total (aka pooled) CV (see this article). There is an infinite number of combinations of CVinter and CVintra which will give the same CVtotal.
$$\begin{matrix} s_\textrm{inter}^2=\log_{e}(CV_\textrm{inter}^2+1)\\ s_\textrm{intra}^2=\log_{e}(CV_\textrm{intra}^2+1)\\ CV_\textrm{total}=\sqrt{\exp\left(s_\textrm{inter}^2+s_\textrm{intra}^2-1\right)} \end{matrix}$$

“We added two numbers and their sum was five. What were the two numbers?”

Leaves the pupil – rightly – dazed and confused.

Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz

The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes
23,225 posts in 4,879 threads, 1,652 registered users;
33 visitors (0 registered, 33 guests [including 8 identified bots]).
Forum time: 23:46 CEST (Europe/Vienna)

We absolutely must leave room for doubt
or there is no progress and no learning.
There is no learning without having to pose a question.
And a question requires doubt.
People search for certainty.
But there is no certainty.    Richard Feynman

The Bioequivalence and Bioavailability Forum is hosted by
Ing. Helmut Schütz