Statistically significant page impressions

How many does it take?

[farmboy]

If a channel has 2 page impressions and 1 click, that's a 50% CTR. However, with just two page impressions you can't depend on that data to predict future activity, conduct analysis, etc.

So how many page impressions are necessary to have useful data? 100, 1000, 10000?

FarmBoy

[ken_b]

On low traffic channels, under say 25 impresssions per day I'll look at a week at a minimum, preferably a month.

On higher volume channels with thousands to tens of thousands of impressions per day, I'll look at a day or two, maybe a week.

Partly it depends on what I'm trying to find out.

[ken_b]

I worded that poorly, on my site "tens of thousands" would be for a sitewide number, not a single channel.

[Vadim]

According to the statistical science to have 10% error in the estimation you should have 100 clicks and 30% error - 10 clicks. The absolute error is about the square root of the click mumber.

Also the natural period is the week because in most cases the number of clicks are different in weekends.

So I would say you need not less than 10 clicks (better 100) and at least one week to be sure.

Vadim.