How many installs / impressions are needed for a statistically significant IPM on Facebook?

Question

We are buying on Facebook.

We are testing creatives until it reaches 50 installs or 10,000 impressions. We can't afford to spend too much on creative but I don't want to miss out a winner because we killed it too fast.

What are the best practices here?

Answer 1

If you would like to identify the winner faster, than having 50 installs, you could test new creatives only in one placement (FB newsfeed) in the separate campaign and later add the winner to the standard campaign.