In his third article on the "accuracy" of Google's AdWords, ThinkMetrics' CEO explores the company's explanations for discrepancies.
My last few columns have focused on the accuracy (or otherwise) of Google AdWords click-tracking and billing system. AdWords earns Google over $1 million per hour, 24/7, which makes it the most important web analytics system on earth. The accuracy (or otherwise) of that system underpins the most important financial institution on the web.
In the first article I described problems I had personally encountered. On some occasions AdWords was billing me for much greater volumes of traffic than I could account for using both my own and Google's own web analytics systems. Two different systems that confirmed each other's numbers, yet disputed the AdWords' numbers, raised the issue of how accurate Google AdWords was when it came to counting clicks and generating bills.
In the second article I covered Google's response, which was that the AdWords system is always 100 percent accurate. According to Richard Holden, Google's director of product management, the click-tracking and billing system of Google AdWords never makes a single mistake-- ever. Holden explained that, in Google's view, if you complain about billing accuracy it is merely a sign you need to be educated as to the error of your ways. Since, in Google's view, AdWords can never make a single mistake, if your numbers disagree with its, your numbers must be wrong.
Google's role is therefore to explain to you why your system has come up with different, incorrect, numbers. As a consequence of this, Google simply does not have a mechanism for checking the accuracy of AdWords. Where most companies would have a complaints' investigation procedure, Google has a customer re-education process.
Google's primary educational tool is a single web page on its website. This document seeks to explain why AdWords and Google's own Google Analytics may report different numbers. Some, if not all, of the arguments contained in this page will apply to other web analytics systems you may be using.
In this article I will list each of the reasons on Google's web page, and analyze its validity.
Why AdWords and other web analytics systems may differ (according to Google)
Different Terminology
"Make sure that you're comparing equivalent items. Google AdWords tracks clicks, while Google Analytics tracks visits. If a user clicks on your ad twice within thirty minutes without closing his or her browser, this will be registered by Analytics as one visit to your site, even if the user left your site and then returned shortly after. For example, if a user clicks on your ad once, clicks the 'back' button, and then clicks your ad again, AdWords will register two clicks while Analytics will register one visit."
This is perfectly valid reasoning and this situation will lead to Google AdWords' count being higher than yours. The formal definition of a visit is "a series of page requests with a gap of no more than 30 minutes between each one." If someone leaves your site, then returns within 30 minutes, it's still the same visit. Technically it's two separate sessions, but most analytics systems don't report sessions.
It's not uncommon for this to happen, especially if you're selling online. People will want to compare your site against your competition before making a decision. In fact, it is rare for a purchase to happen on a first visit. Whether someone is likely to return within 30 minutes or not depends largely on the nature of the purchase. The more expensive the purchase, the longer it will take for them to weigh up the opposition and make a decision. Sites selling mortgages and loans may see repeat visit cycles measured in days or even weeks rather than minutes, whereas the DVD sales cycle can be fairly short.
You are best placed to understand what behavior your visitors are most likely to exhibit in this regard. However, in my experience the degree of discrepancy between Google AdWords and your own analytics system due to clicks versus visits is unlikely to be more than a few percentage points.
AdWords Filtering
"AdWords automatically filters certain clicks from your reports, while Analytics will report on the resulting visits to your website. The clicks we filter from your AdWords reports are the occasional instances of someone clicking repeatedly on your ad in order to increase your costs or to increase your clickthrough rate. AdWords considers these clicks to be invalid and will automatically filter them out of your AdWords reports. You are not charged for these potentially invalid clicks."
Google will not count as two clicks someone who double-clicks hyperlinks because they think you have to double-click everything. Google will also filter out any intentional click fraud they detect.
Click-fraud can happen for two reasons: a competitor may wish to blow your budget and kill your ad, or someone might be trying to make some money off you. Affiliate sites get 50 percent of the revenue Google earns if you click a Google Ad they are running. So it's in their interest to boost the clicks. There are companies (mainly in India) who boast sophisticated technology to do this for the affiliate in a manner which is hard to detect. Affiliates do deals with them and split the revenue.
Google states this is a minor problem which they are on top of. Others suggest it is a major industry earning millions, if not billions, of dollars. Google replies these people are inflating numbers for their own purposes. Google refuses to disclose the exact scale of the problem, but where they have been sued over this, they invariably settle out-of-court for multi-million dollar sums. If you believe click-fraud has cost you money I suggest you sign up with your nearest class action-- there's bound to be one available.
If your AdWords are being filtered by Google for invalid clicks, this will push the AdWords numbers down. Invalid click filtering will never cause AdWords to have numbers higher than your analytics system.
URLs Not Tagged
"If auto-tagging is turned off and the Destination URLs do not contain manually tagged campaign tracking variables, the visit will not be marked as Google CPC, but instead may be attributed to Google Organic. Please ensure that your AdWords' account either (1) has auto-tagging turned on or (2) has campaign tracking variables appended to the end of every destination URL."
While this rule is phrased in a way that refers to Google Analytics, the logic holds for any other web analytics system. If you don't add some form of tracking parameter to the link in your ads that leads to your website, your system won't be able to tell the visitor came from that ad. This also requires that your system is set up to count and report these parameters. This should be self-evident, but the majority of Google Ads do not contain any tracking parameters (see my article "What Analytics Do You Use?").
If you are complaining to Google about the AdWords billing and you are guilty of not using tracking parameters, Google is quite right-- you do need educating.
Not just any old tagging will do if you want to argue with Google. You need to ensure your tagging matches their billing. If you are being billed separately for five different ad groups, you can't put together a strong case if you're using a single parameter that amalgamates them all into one. If your total doesn't match theirs, you need to be able to drill down and pin-point exactly which ad group you believe is being over-charged. In other words, you need a tracking parameter that corresponds to each individual billing line in your AdWords statement.