Does Adblock Matter For Your Site?

Does ABP Matter?There’s been some controversy about the ethics of using Adblock. Webmasters want advertising income, users want a better browsing experience. Yadda yadda yadda. I can certainly sympathize with both sides of the debate – on the one hand, I hate intrusive ads as much as anyone. On the other hand, this site is mainly ad-supported.

But enough about that. If we lay aside the morality debate, do you know how big is the real impact of Adblock users on your site’s financial success? Perhaps you’re only “losing” 0.1% of your potential ad impressions. Or it might be over 50%. In any case, it wouldn’t hurt to have some actual numbers, right? I’ll show you how to get them.

Nuts And Bolts

We’ll need two things – a way to detect the Adblock extension, and a way to track the number of visitors that use it. For the first part, there’s a simple JavaScript solution posted in a StackOverflow thread that we can adapt for our needs. With a few minor changes, this script seems to work nicely with the latest version of FF and correctly detects Adblock Plus 1.0.1.

Tracking the Adblock users is a bit trickier. There are two choices here – either write a specialized web stats tool (a marvelous waste of time), or try to integrate the detection script with your existing analytics software (requires grokking the API). I decided to go the second route and use Google Analytics custom segments for this task. If you’re already using GA on your site, creating a custom segment is relatively painless (more on this later) and you get all the advanced reporting with no additional hassle.

Bringing It All Together – The Tracker

Place the below piece of code on every page where you want to track Adblock users. It doesn’t matter where exactly you put it, as long as there’s the GA tracker code on the same page, too.

Sidenote for WordPress users : The easiest way to install this script on your site is to put it in your theme’s footer. Go to Appearance -> Editor, click on Footer and paste the code just before the </body> tag.

<script type="text/javascript">
/* <![CDATA[ */

function checkAdblock() {
	if ( detectAdblock() ){
		trackAdblock('Adblock Detected');
	} else {
		trackAdblock('No Adblock');
	}
}

//Run checkAdblock when page is loaded
if(document.addEventListener)
	document.addEventListener("DOMContentLoaded", checkAdblock, false);

//adapted from http://stackoverflow.com/questions/2472/how-can-i-tell-if-a-web-client-is-blocking-ads
function detectAdblock(){
	//Create an invisible test image 
	var AbpImage = document.createElement("IMG");
	AbpImage.id = 'abp_detector';
	AbpImage.src = '/images/ad/banner.gif';
	AbpImage.style.width = '0px';
	AbpImage.style.height = '0px';
	AbpImage.style.top = '-1000px';
	AbpImage.style.left = '-1000px';
	document.body.appendChild(AbpImage);
	//Check if Adblock has tried to hide the image
	var AbpDetected = (ws_getComputedStyle(document.getElementById('abp_detector'),'display') == 'none');
	//Be nice - remove the image 
	document.body.removeChild(AbpImage);
	return AbpDetected;
}

//http://www.robertnyman.com/2006/04/24/get-the-rendered-style-of-an-element/
function ws_getComputedStyle(oElm, strCssRule){
	var strValue = "";
	if(document.defaultView && document.defaultView.getComputedStyle){
		strValue = document.defaultView.getComputedStyle(oElm, "").getPropertyValue(strCssRule);
	}
	else if(oElm.currentStyle){
		strCssRule = strCssRule.replace(/\-(\w)/g, function (strMatch, p1){
			return p1.toUpperCase();
		});
		strValue = oElm.currentStyle[strCssRule];
	}
	return strValue;
}

//Record Adblock state  
function trackAdblock(state){

	function readCookie(name) {
		var nameEQ = name + "=";
		var ca = document.cookie.split(';');
		for(var i=0;i < ca.length;i++) {
			var c = ca[i];
			while (c.charAt(0)==' ') c = c.substring(1,c.length);
			if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
		}
		return null;
	}

	var current_cookie = readCookie('__utmv');
	if ( (current_cookie==null) || (current_cookie.indexOf(encodeURIComponent(state)) == -1) ){
		//Set the user-defined segmentation variable with the Google Analytics tracker
		if (typeof pageTracker != 'undefined'){
  			pageTracker._setVar(state);
	  	}
	}
}

/* ]]> */
</script>

Sorry for the lack of indentation – it looks like my syntax highlighter plugin has a few glitches.

Viewing The Results

Now that you’ve installed the tracker, you’ll probably want to verify that it’s working and see the promised statistics. To do this, you need to create a custom segment in your Google Analytics report. Okay, that’s an easy one.

1. Go to “Advanced Segments” and click on “Create a new customised segment”.

Create an advanced segment

2. Expand the “Visitors” list and drag the “User-Defined Value” block to the empty box on the right. Select “Matches exactly” from the Condition dropdown, and enter “Adblock Detected” in the Value field. Finally, enter a suitable name in the Name segment : field and click on Create Segment. You can also click the Test Segment button to check the segment before saving, but this will only work if the tracker has already been running for a while and has recorded some hits.

Drag & drop the "User-defined Value" to the criteria field

3. Now, go back to the Dashboard and select the newly created segment from the “Advanced Segments” box.

Select the custom segment

The result :
Adblock usage stats in Google Analytics
Note that you’ll probably need to wait for a few hours – or even a full day – before the new stats show up in Google Analytics.

Final Mini-Rant

On a more personal note, it appears that only 5% of my visitors use Adblock. I believe this hardly merits more than a “meh” reaction :P

And in case anyone cares about my stance on the ethics of ABP : at this point in time, there is no proper solution. Everybody wants free stuff. Everybody wants money. Consider the digital piracy debate – Adblock vs. Anti-Adblock is a more subtle manifestation of the same issues. And it doesn’t look like there’s a way out, not until we hit some kind of Utopia.

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8 Responses to “Does Adblock Matter For Your Site?”

  1. Adam Dempsey says:

    Thanks for the info, going to try it on one of my bigger sites, be interesting to see how many users actually do block ads!

  2. asf says:

    this is a waste of time, people with adblock would not click ads anyway

  3. White Shadow says:

    @ asf : Wow, haven’t heard that one before /s

    But really, there is something to consider here.

    If lots of visitors use Adblock, it’s obvious they’d be unlikely to click the same old ads even if you manage to circumvent Adblock. However, the site owner could try different monetization techniques – for example, in-context affiliate links, merchandise, or even a paid subscription model. But first they need to check if there is an actual problem in the first place, which was the whole point of this post.

  4. Brian says:

    @White Shadow
    “in-context affiliate links” – adblock blocks many affiliate links too.

  5. White Shadow says:

    Hmm, didn’t know that. Blocking affiliate links seems somewhat dubious to me – after all, a simple text link lacks the annoying qualities of most ads, and doesn’t really hurt anyone.

  6. Jeroenz0r says:

    I googled for “check if client has adblock has installed” becuase I didn’t knew how some pages see if I use ABP :)

    I’m one of your 5% then :(

  7. DavidM says:

    @ asf

    Are you sure Adblock users wouldn’t click ads by accident? Many sites have ads cleverly immersed in the content, sometimes to where users can’t distinguish between the two.

    Whatever the case, it’s no big issue to me. I’ve always hated intrusive ads. While I don’t use Adblockers, I don’t see anything remotely unethical about them, especially given that some people just don’t want to chance unethical ads showing up on their screen.

    As for myself, I always try to make my ads fit my content, make them relevant. If they’re not, I’ll usually joke about the fact. If users block the ads, so be it. May 1000 African flees infest their armpits!

  8. Craig says:

    There seems to be a growing movement to block Google Analytics (adding it to the ABP filters list). Sadly, this technique won’t track those folks.

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