> Don't forget that Chrome users are more tech savvy on average than Firefox users
I somewhat doubt that. They're both mostly non-default browsers where they are used (and the places where Firefox is default probably have more technically savvy users than those where Chrome is default), Chrome has far and away more current mindshare and is, therefore, probably more likely to be a crowd-inspired (rather than technically-inspired) choice as a non-default browser. I suspect that there was a time when your statement was true, but I don't think its true now. (Though inertia in both camps may make it true even when its less likely to be true for new users.)
I don't doubt that Chrome has a lower (real or, even moreso, measured) CTR, I just doubt that its particularly because Chrome users are more tech savvy.
Tech savvy isn't the only explanation for CTR differences, especially measured CTR difference; ISTR a while ago discussions of what was possible in Chrome v. Firefox for adblocking, and from that it seemed that Chrome ad blockers would still download (but not show) ads, while Firefox wouldn't download them. Don't know if that understanding was accurate or if it is still the case, but that could conceivably result in Chrome impressions being overstated (and CTR being understated) relative to Firefox.
Anecdotally my experience has been quite the opposite. I know a few developers who primarily use Chrome, but besides that the rest are people that heard it was faster, or installed it by mistake as part of a bundle.
I actually don't disagree with this. Even though I'm a pretty tech-savvy Firefox user (and by "tech-savvy", I mean "seasoned Unix administrator and backend programmer"), "Mozilla" is also a household name among plenty of less-tech-savvy folks; I've seen Firefox (often called "Mozilla" or "Netscape" by its users, amusingly enough) everywhere from the most high-tech web development shops to computers owned/operated by seniors and running Windows XP and dial-up internet. Chrome hasn't had that level of adoption yet; while it's certainly popular among the tech-savvy, it hasn't trickled into ordinary households quite the same way as Internet Explorer and "Mozillafire Netfox" have.
It helps that Firefox has a lot of brand maturity in non-tech circles, whether it's referred to as "Firefox" or by the names of its ancestors. It also helps that Firefox is the default browser on the vast majority of desktop GNU/Linux distributions (which are gaining some popularity now that Windows XP is unsupported and being phased out more aggressively), though this probably isn't as significant of a factor as the existing brand recognition/maturity.
Even a large difference in CTR wouldn't necessarily say anything about being "more tech savvy". A sub 0.2% difference between Firefox and Chrome is therefore meaningless in this context. That's making the heroic assumption that Chitika Insights data is not biased in some way and can overcome methodological problems (no script, user agent changes, bots clicking ads) even if it was perfectly representative.
