One of the strangest things about online advertising, is that results for most campaigns stay pretty consistent over time. If a campaign starts off with a CTR (the ratio of clicks to impressions) of 0.5% on a site, then it is likely that it will remain at that level throughout the campaign. What this means is that every day roughly the same amount of people on that site click on the ad – which is strange because it implies a uniformity in people’s thinking/behaviour patterns which you wouldn’t expect.
To put it another way – do you think that you react the same to advertising as most other people with vaguely similar traits to you? No? Well statistically speaking – you’re wrong! That’s not to say people aren’t different, only that if you show an ad to two different groups of 1,000 people, about the same number from each group will click on it.
Why does this matter? It matters because it means that when you look at the stats for your ad campaign you can judge it more effectively, as you can be fairly sure that the stats you see won’t change much. This isn’t always true of course – over a long period of time the CTR of most campaigns will drop, and there will always be the possibility of strange and random turns of events, but generally speaking the CTR of your campaign will be pretty stable – once you’ve delivered enough ads that is.