could moving the code further down your HTML also play a part?

I doubt it, but who knows for sure?

I'm more inclined to think any eCPM issues revolve around the specific page and where the ads actually appear on that page.

In my case, on some pages, I have some ad code way down on both the source and visible page. The ads that appear at the end of the page and code often pay better than those higher up the page.

But that's on pages where the first ad is high in the left hand column and the other ad block is at the bottom of the center column, well below the fold, (at 1024x768 browser window).

On pages where the first ad block is higher in the center column that block usually beats the other ad block that is at the top of the right hand column.

But all together those type pages make up only a small fraction of my site.

My most common page layout has a 160x90 adlinks unit in the left column, right after the first paragraph of content text and a 300x250 regular adblock right under the main topic image in the center column. That puts the adlinks well above the fold and the 300x250 at least partiallyabove the fold on most pages.

On those pages the regular adblock now always performs MUCH better than the adlinks unit, which has its code pretty close to the top of the source page.

I've experimented with the ad block in the center column when I have more than one image to display on the page.

It doesn't seem to make a difference for my eCPM if I put the adblock under the first image, or down below the last image, even though putting the adblock under the last image puts the ads well below the fold.

But again, I think this stuff really depends on the page content more than where the ad code appears on the source page.

@londrum Is it possible that with your old layout, there was a delay between the add loading and your content loading - making visitors notice the adds more

only for a split second... maybe one second tops. enough for the designer to notice a flash of white screen, but not enough for a visitor to care about.

That's a good question. A few months ago, I changed the html code of my navigation left column with the list of latest articles to appear at the bottom of the source code for SEO purposes. It was a test, I can't say for sure if it helped. Visually, in terms of layout, there's no difference because I still float it to the left with CSS, but the Adsense ads does take a bit more time to appear and the general CTR have gone down since. However, it is hard to point the blame with the current economy and the weaker summer season. I'll have to check this further.

My gut response is that because you changed the HTML, adsense has reset some of your... lets call them parameters, so you aren't getting the same payout at the moment. I would be interested to hear how the longer term trend is, if you leave in place.

But you say ECPM has changed - which element? CTR or CPC?

adsense has reset some of your... lets call them parameters

I've always thought that parameter is supposedly called Smart Pricing? I very much doubt that with the same quantity of ad space moving the ad position would alter the EPC.

I do assume that the advertisers are as before?

But you say ECPM has changed - which element? CTR or CPC?

Yep, one of these have been affected therefore more traffic clicking less or your actual EPC being reduced?

i think it was probably something to do with the ad appearing a split second before the content. maybe that was just enough to focus people's eyes on it.

but it was only a one second difference, tops.

i've changed it back now. i can put up with the flash of white screen if it means more clicks.

I've always thought that parameter is supposedly called Smart Pricing?

Well, yeah, but I was thinking more of the adsense bot thinking [1] 'what? the page has changed? Wait! This page could be about anything. I'll just turn things down a bit while I figure out what its new topic is' sort of thing.
IMHO

[1] the bot doesn't think? Ha! I laugh at you! It knows *exactly* what it is doing! ;)

In my case, one of my completely redesigned websites had its AdSense code moved further down the pages.

Following few days: eCPM/Earnings sky-rocketed - I was on the moon!

Next couple of months: Earnings/eCPM nose-dived to the depth of pits

But I didn't panic or change anything (from quality and user-exp POV, the redesign was very important for me to keep.)

It took nearly 3/4 months for AdSense to get back to pre-redesign levels. Now it has started to improve slightly more than pre-design times (considering all else being equal.)