4-link linkunit showing less than 4 links.

What causes that?

[Perfection]

I've been using a vertical 4-link linkunit on my site, and I've noticed a lot of times some pages show less than 4 links. Sometimes there's 4, sometimes 3, sometimes 2, and sometimes 1.

Sometimes the linkunit looks like this (the way it is supposed to look):

Ads By Google
Widgets
Red Widgets
Good Widgets
Widgets For Sale
__________________

And 10 minutes later it can look like this:

Ads By Google
Good Widgets
.
.
.
__________________

. = blank space

I've noticed the less links shown, the lower my CTR is. And, besides the lower CTR, it just looks funny with this big unused blank space.

What causes this to happen?

I could see it happening as a result of too little text on a page, but that isn't the case here. For a month one page has shown the full 4 links every time I've looked, and for the last week or two the same page has shown just 2. The content of the page hasn't been changed.

What's that about?

[hunderdown]

Look for info. at AdSense Help on expanded ads. they are supposed to pay better than regular ads but obviously that's not always true.

[Perfection]

I know all about expanded ads, but those are on adunits. I see them all the time. These are linkunits. The text links that appear on someone's site aren't actual ads. They are just subject links that, when clicked, bring a person to a page of ads about that subject.

These are almost like expanded subject links, which doesn't really make much sense.

[hunderdown]

Sorry, I didn't read your post carefully. Perhaps AdSense is experimenting. Maybe they've found that one subject out of the four is the one that people coming to your site usually click on. So now they are highlighting it, in the way that expanded ads highlight a text ad?

[Perfection]

That would make sense, but I've actually seen a lower CTR, lower eCPM, and a lower amount of money being made when the linkunit shows 1 or 2 links instead of 4.

The out-of-place empty white square it causes when the full 4 text links aren't showing isn't my favorite thing in the world either.