Hi all:

I just don't quite have the chops to do this myself. Any help appreciated.

Want to test marketing to an audience, see how it works. If it works, throw more money at marketing to that audience.

Q: How many people do I have to hit to get statistical significance, so I can feel confident that the next time I market to that audience, the results will be similar?

Basically just want a two-cell spreadsheet:
-
Enter: My predicted conversion percentage. (If I hit a thousand people, what percent of people will "convert"?)

Result: You need to hit ### people to be sure that the next mailing will deliver the same conversion rate, +/-10%, with 90% accuracy.
-
Looking to calculate ###.

(+/- 10%, btw, means if I get a get a .5% conversion rate, I'm 90% sure the next attempt will be between .45% and .55%)

Row 8 of this spreadsheet gives the necessary formulas:

https://vwo.com/downloads/ab_testing...calculator.xls

I just can't figure how to reshape them into the Result cell as described.

I don't care about A/B testing for this, BTW. Just the Result described above.

Thanks for any help!

Steve