I am curious, what constitutes “traffic”, and if it is page loads, why is it the right thing to measure? Users who load the page are already visiting, regardless of whether there is an ad on the page or not. (Or does it include a delay to filter visitors who immediately close the page?) And they did not know in advance whether there was going to be an ad, so their decision to visit the site is not based on the presence of ads. (Unless perhaps if they had a particularly bad experience a previous time — bad enough to remember the domain and not follow the link.) I don’t understand how turning ads on and off every two days can be used to understand long-term effects. There appears to be the assumption that there is a relation between a user seeing an ad or not, and subsequent traffic. There might be a small correlation because of visitors browsing the site, or likeliness to share, but if outside of the spikes, the majority of visitors arrive from an old external link or search engine, and they only read a single page, then how does turning ads on and off every two days measure impact on these users?