(12C) Binary Outcome

[Gamo]

Suppose you want to test whether more people respond to one drug versus another, or whether one advertising campaign is more effective than another. In either case, you have a binary outcome. Someone either responds to the drug or they don't. They either buy the product or they don't.

In either case you have a probability of something happening, P1 for one group and P2 for the other , and you would like to test whether the two probability are different enough to tell apart that their difference is statistically significant.

If you are designing an experiment, how many people should use in each group?

This program estimate n, the number of subjects you need to assign to each, based on you initial guesses at p1 and p2

Program:

Code:


01 STO 1
02 Rv
03 STO 2
04 RCL 1
05 RCL 2
06  +
07  2
08  /
09 STO 3
10  1
11 ENTER
12 RCL 3
13  -
14 RCL 3
15  x
16  1
17  6
18  x
19 RCL 1
20 RCL 2
21  -
22 ENTER
23  x
24  /
25 FIX 0

Example:
Suppose p1 = 0.1 and p2 = 0.3

.1 ENTER .3 R/S > 64 with two group total > 2 x > 128

You need 64 subjects per group.
n is the number in each group, so the total needed is 2n then total for both group is 128

Note that this is only a rough estimate good for quick estimation.

Gamo