Not too long ago, I said that I wouldn’t plant any Google AdSense link units on this blog:

I know Google is really pushing the link units. I got a rare email from AdSense recently, urging me to implement them. I don’t plan to. I can see why they perform so well — they blend in so unobtrusively that I’m sure they generate plenty of action just on accidental click-throughs. But to me, they seem to cross the line in terms of the editorial/advertising divide. I’d rather not go there.

Well… As you can see by looking at the skinny bar atop this page, I’ve gone there. I planted a bank of link units above the site header, starting yesterday.

The reason is simple: Ad revenue has been tanking around here lately, so the experimentation continues. A little research yielded commentary by full-time webmasters (the links to which I cannot rediscovery tonight, drat it) suggests that link units tend to generate more bang per click. I was skeptical, but I figured it was worth it, if only to reclaim some above-the-fold space that the previous leaderboard ad unit took up.

The other nuggets I came across: Apparently, the optimal AdSense configuration is not to place the maximum three ad units per page. If you’re getting millions of hits, then you can certainly max out; otherwise, you’re better off limiting it to one or two traditional units, along with a link unit. The reason is that Google limits the inventory of ads it serves up; and since priority goes to the first instance of AdSense code on a page, that can result in ads appearing only in the top-most unit and nowhere else. That happened pretty regularly on this site, with the result being a big empty green space in the left sidebar, which I detested (there’s a javascript trick you can use that eliminates that, but it was a bit buggy when I briefly implemented it). I’m thinking the link unit’s placement will now default the “first” unit status to the sidebar’s wide skyscraper, which will ensure that something will always appear in that space. Hopefully, that translates into more clicks overall too.

In this very early going, revenue’s about the same as it was before the switch. It’ll take a couple of weeks to really get a good read on this.

Related to this, I’ve slapped half-banners into the comment/feedback popup boxes. The Yahoo! Publisher Network ads that were previously in there? Absolutely no action, and laughably inept at serving up relevant ads. As of now, I’m giving up on YPN, as it looks like it’s got a long way to go before it’s worthwhile (if ever).

Anyway, as always, this post is more for my records than the readers’. Carry on.