# Discrepancy in minimum sample size formula and what's being used in the worked out example at 08:22

**at 08:22 (time in video)**

in example of calculation of minimum sample size;

*p = Pooled proportion = (µ1 - µ2)/2*

*but, actual calculation is (0.33 + 0.33 + 0.02)/2*

**HOW???????**

4 answers ( 0 marked as helpful)

can anyone plz clarify this?

I am jumping on to this one, too. The code is not compatible with the equation in the video.

See 7:37.

*"µ2* is the desired proportion of the test group because we don't have it yet"

We want to see a change that is greater than the MDE (previously worked out at 0.02), so the mean desired proportion of the test group would be the mean dp of the control group + the mde.

Perhaps, confusion is due to round-off value, 1.73% = 0.02 ?

and the formula for pooled proportion is (mu1+mu2)/2 ?