It is relative. 75% of 100 clicks per day is not a big deal. 75% drop from 1,000 clicks per day is noteworthy.

Ah that's a good point! Around 300 clicks.

yes, it happened with my account for no reason, but recovered after five weeks, luckly. but don't know if it will come again. If you did nothing wrong, you don't need to worry then. Because it is too bad to be real.

75% is 75% is 75% whichever way one looks at it.

You write 300 clicks per day. Are you saying that you used to average 250~350 clicks per day but are now getting 75 per day, say 50~100?

That's a massive drop and is very noteworthy, in my sector that would be like losing $120+ per day.

Your PVs have not changed, when you write 300 clicks do you mean AdSense Page Views or actual AdSense clicks?

FWIW the last few days I have seen overall PVs drop by 30% however it is on one particular section of one specific site that has always had my lowest CTR, a very low CTR.

The overall result has been that actual clicks and earnings have stayed the same however my CTR has risen dramatically.

Basically either the ads have changed or the visitors have changed. Most likely either the good inventory isn't there at the moment or Adsense's algorithm is mistakenly putting in less suitable ads based on the wrong keywords.

I have had CTR fade to almost nothing and then come back more times than I can count. I know from watching my site over a period of years that the best CTR is at times when I get ads for events such as concerts or festivals and these aren't consistent across the year.

The last couple of days have been poor for me and looking at my site now I see off topic ads including one so far out that I am about to block it.

I am assuming of course that you are talking about a drop in the total number of clicks rather than a surge in visitors from a new source who are not clicking and distorting the percentages without affecting cash income.

Losing 275-ish clicks per day in most niches might not be noticeable, but setting that aside, what's more important is earnings. Have earnings dropped?

Here are some possible causes:

Technical
- JavaScript conflict
Third party code is constantly changing, particularly Social Media plugins and AdSense. A change to one can cause AdSense ads to stop functioning properly. Typical malfunctions include losing the ability to be clicked to a distorted and unattractive display.

- Device incompatibility - your site
Your site could be displaying in a distorted and unattractive manner, causing visitors to back out. Check your analytics and review your time on page type stats.

Device incompatibility - ads
Ads might not be showing on certain devices or clashing with site design, resulting in less clicks. Check your analytics for devices used to access your site then troubleshoot those devices.

Browser incompatibility
This is a big one, often relating to CSS or coding errors. Many templates are sloppily coded to work well in Apple devices but not across the range of Windows based devices, despite the best intentions of the designers who may have tested their work in browser/OS emulators. For example, failure to properly display in IE 8 is practically endemic to WordPress templates. This is not limited to WordPress. Check your analytics to see what browsers/OS combinations are popularly being used to access your site and troubleshoot. Also run your code through the W3C Validation Checker.

Hacking
Are all of your server, CMS, and add-on/mods patched and up to date?

Auction related
- An advertiser backed out. A provocative high click (and possibly low paying) ad might have dropped out.

- An ad at the top of the page is attracting more attention.

- Season/event driven clicks dried up at the end of season/event

Also the one or more of the lucrative advertisers' budgets might be up. It's the end of the month.

Basically the drop was all in one ad unit which I was getting the best ctr from!

Which no matter how you put it, it doesn't make sense. If the ads are no longer relevant then why wouldn't the other ad unit be affected?

@anarki was the ctr drop you had on all ad units or just one?

Which no matter how you put it, it doesn't make sense. If the ads are no longer relevant then why wouldn't the other ad unit be affected?

When it comes to money spent on advertising, everything makes sense. Very few advertisers spend money without justification. You just have to look and it's usually there. Just don't look for answers in the AdSense control panel. You won't find it there.

Staring at your AdSense control panel will NOT give you answers. Maybe some day Google will provide better data for understanding CTR drops, but right now that's a current shortcoming of the AdSense control panel. Do NOT seek answers there, you won't find them. You won't find sense there.

Dig into your analytics and all of the other points I and others raised. Consider doing more homework and THEN it will start making more sense.

Regarding your "other" ad unit, it's in a different spot, right? That's a reason in itself why it wouldn't be affected. An advertiser might be targeting a specific area OR your site visitors might not be reaching the bottom of your pages or they have consumed enough content before they reached those ads. Ads are consumed as content. The location of ads can be thought of as Content Blocks within a web page as content blocks.

What about the size, is it a different size? Different ad sizes show different ads.

We can't do your analysis for you. But we CAN tell you what to do to find the answers. Next step is yours. Do it and report back what you found.

Good luck.

[edited by: martinibuster at 2:51 pm (utc) on Oct 30, 2013]

This is something I posted just yesterday in the AdSensePanel in response to someone blaming his roller coaster earnings on Google's experimenting with ad styles. Some of it may apply here:

It helps to know something about how AdWords works to understand what all goes into the value of a click. There are so many variables now (and believe me, because I have the added fluctuations of seasonal sites, I vary from days with mid to high five figure earnings, down to slow periods where I barely make twenty or thirty bucks)

So what goes into a click? First of all, there's an ad auction, with advertisers competing for your placements. Each one of those advertisers have issues of their own that come in to play - daily budgets, max cost per click, quality score, dayparting in some cases, ad sizes available for display ads, geo location if applicable, varying bids by device type, etc.

Then there's the stuff that goes on at your end - your placements, your ad styles, smart pricing, traffic quality, user intent, and in the end, what the user actually clicks on. Your top ad in your top spot might be paying out five bucks a click, but for whatever reason, the users are most interested in the last ad in the last ad unit, which pays three cents. Oh well.

Then you add in the whole click fraud detection system (which personally I think *might* be a tad aggressive, but on the other hand I see so many flagrant violations out there in the wild, maybe not aggressive enough) with click networks and bots and I dunno what all - that all has to be sorted through and the bad guys filtered out.

And then on top of that - user behavior has just plain changed since 2004. Users are definitely becoming ad blind; in certain sectors you see heavy usage of ad blocking technology, and pile the whole mobile thing on top of it, and it's a wonder we see any stability at all.

Yea, I'm sure there is AdSense experimentation (we've all seen it) but as a percentage of the whole, considering all that stuff up there ^^^ and other factors I don't know about or have forgotten, it's hard to really blame too much on the experiments.

If I'm to believe the ZDNet post about it, (and I don't know how accurate it is - nobody does but Google) AdSense is seeing some decline as well.

I kind of think that roller coaster is the name of the game for AdSense in 2013.

Thanks netmeg! That's a whole pile of SENSE. It's easy to kick the AdSense box and declare it's broken or doesn't make sense. But a serious publisher is going to dig in and consider ALL of the factors we named and more that go into making a click.

It does make sense. Sort of. ;)

And I completely forgot to mention the other ad networks, interest based advertising and remarketing. Ad or category blocking, advertisers blocking publishers (oh yea, they can do that you know), publishers allowing text or image ads or both, etc etc etc.

I would like to publicly thank Netmeg and martinibuster for their great advice!

So basically I took another look at the ad units and noticed that the ad unit that went down was a square 336 by 280, the other one that stayed the same was a smaller square 300 by 250. I decided to experiment by switching the 336 by 280 to 300 by 250 and it did go up quite a bit (not quite up to what it was before but much better then it was.)

Now that I'm aware what a difference the different sizes can make, I am thinking that I should have those two sizes somewhere else on my site, in spots that don't perform as well (by me it's the post pages)and keep a constant eye on them, and as soon as I see that one is doing better than the other to then switch my hot spot ad to that size.

Question: Do you find that one size square performs better then the other?
If you allow text ads and image ads is there a way to check how each one performs separately?

nickys (& others): No matter how long you've been a publisher, it's a good idea to experiment now and again with ad sizes, types, etc. Personally I find the 300x250 more profitable than the 336x280 even though the bigger rectangle will back-fill with the 300x250 ads. I do AdSense experiments every few months just to make sure I'm optimizing the ad space.

At the moment, most of my sites are WordPress, so I'm using an advertising plugin to rotate ads - I'll create two almost-identical ads, say one with red links and the other with blue links, and assign a 'red' channel to one and a 'blue' channel to the other, and I rotate them evenly till I get enough data (usually 10k impressions does it for me) to decide which does better.

Likewise, I'll make a text only ad and an image only ad and run them against each other. Or one with borders, and one without. Or different backgrounds.

Before I moved to WordPress, I just ran up a little PHP script to rotate them.

Of course, it's not a true A/B split, because there are all kinds of things going on at the Google and advertiser end that we can't control and don't even know about, but it at least gives me a little insight to make what decisions I can.

As far as ad sizes - the top recommended ones always have worked best for me. They're the IAB standards, and that's what I make room for when I design the site. I've never used a 336x280 because my sidebars aren't that big, and I don't want anything that big in with my content. On the other hand, I resisted the 728x90 for years, and just used the 468x60 - finally got tired of Google nagging me to try the bigger one so I gave it a test and like within an HOUR earnings had gone up significantly (and they've stayed there)

Test Test Test, and don't be afraid to test their suggestions. It might not work, but you won't know till you try. And Google has more stats than you do.

I also use wordpress. What advertising plug in do you use?

AdRotate Pro

I don't think many adsense publishers realize that adwords campaigns can see the value of the clicks your site provides, they know what they paid and know what the return was. Adsense adjusts for this automatically to a certain degree but the advertiser can manually exclude your site as well.

My best results have been with text only units and so it doesn't matter as much what size the unit is. I did however finally listen to a Google request to try an ad link unit and was pleasantly surprised.