(12C) Binary Outcome

[Gamo]

Here is more information about the formula used.
Note that this is only a rough estimate.

The rule of thumb is based on the assumption of significance α = 0.05 and type II error β = 0.20, i.e. 80% power.

formula:

n = 16P(1-P) / (p1 - p2)^2

where P = p1 + p2 / 2

Thank You Dieter for more indept information with better program alternative.

Gamo