AdSense earnings are very volatile, one can often see large swings in RPM from day to day without changing anything. The fact that one day you're earnings were high and the next very low has more to do with market conditions than ad types. Furthermore changing settings can have a short-term impact on earnings as the system adjusts to the changes, so frequent changes will leave your account in a constant state of flux and that alone can have a big negative effect.

If you believe that text only ads will perform better for you (it is possible) then I would recommend setting up an A-B test in the "Experiments" section of your AdSense account. Like that you can test the hypothesis while controlling for changes in market conditions.

Thanks for the reply. I'd like to clarify that I know for certain that text ads are working better for me. I've done several a/b tests to get to this conclusion. My issue is, that I can't seem to get AdSense to serve text ads anymore. Any suggestions?

Create two ad blocks, one with text only, and one with display ads only. Then you can do whatever you want. You can select for example 75% of the times to display the text ads only block.

if you do this in Javascript you'll use something like that :

if(Math.random()<0.75)
{
// code of text ads block
}
else
{
// code of display ads block
}

In PHP, this should be something like:

if(mt_rand(0,100)<75)
{
// code of text ads block
}
else
{
// code of display ads block
}

Based on this approach, you can even refine the system. Like for example, if you noticed that text ads are performing better with North American visitors, but not with European, then you can use the geo ip of the visitor to change the %

@Dimitri is this against policy or perfectly okay to do?

My issue is, that I can't seem to get AdSense to serve text ads anymore. Any suggestions?

The only way I have found to do this is at the ad-unit level. Set the ad-unit to text only.

is this against policy or perfectly okay to do?

Why would it be? Provided one is certain that only one ad-unit will be loaded on the page it is fine. If for some reason you set your condition such that both could be shown (which is a very unlikely case, impossible in the above example), it may cause you some problems but even then it would be an ad density issue.

A year or 2 ago Adsense themselves gave me this piece of code to use to test an A-B split - much the same code as above but straight from Adsense.

<script>
var random_number = Math.random();
if(random_number < .5) {ADUNIT 1 CODE} else {ADUNIT 2 CODE}
</script>

Has anyone ever ran into issues by using the coding mentioned above for showing 75% text ads with one unit and 25% display ads with the other?

Also, would this lower the bids on these units because they are only showing one type of ad?

Text ads are doing well because they are bidding against other text ads and image ads. Remove the image ads and the auction pressure will decrease, lowering the bid amount for image ads.

For me (as for many of you) Text and Display/HTML5 Adsense ads are the biggest money makers (you can check).
But it depends if G shows Nessie arrows within those ad types on your website or not.
If yes - you are in the game and can see much greater CPMs (RPM).
If not - you have to do everything Nessie arrows to come back.

This is how text ads should look to make you happy -

At the moment I'm fighting Nessie arrows to get back (on mobile devices), because without 'em I can see CPM decrease for about 55%.

The reasons of the CPM drop:
Text ads impressions (show rate) drops from 40% to 20% (more image ads now)
Nessie arrows disappeared from Text and Display/HTML5 ads

Remember: even if you will set ad unit as TEXT ADS ONLY - it will not help you to get back to normal, you will simply get more rubish/irrelevant ads!

My Google manager told me, that there is a fully automatic algorithm, that desides if to show Nessie arrows on your website or if not to show.
So basically you have to monitor your ad metrics, such as Clicks, CTR etc., that all values were not far from the average.

In my case:
I've changed ad style and it has increased the CTR from 0,59% to 0,79%, apparently this became a red rag for the algorithm, which I described above.
Will see how long will it take Nessie arrows to get back.

[edited by: martinibuster at 3:03 pm (utc) on Sep 6, 2018]
[edit reason] Imgur next time. thx [/edit]

And what about case is created adsense text ONLY unit and adsense display images in that place?
Anybodu has similar problem?