So you want to run a Google Analytics audit. Let’s talk about what that means first. The primary reason to run an audit is to check the quality of web data being captured in Google Analytics. What makes the audit process difficult are the various points of failure between data generation on the website and the data being recorded in Google Analytics. Failures occur when source code changes or an unanticipated event occurs. The goal of an analytics audit is to identify the points of failure and validate the data being captured at these points.
This is a primer on how to execute a Google Analytics audit. It assumes that you are somewhat familiar with web analytics audits. If not, read our 5 minute guide on web analytics audit first.
Your Toolkit
The tools to run a Google Analytics audit are many. You can use a generic network capture tool such as Charles or Fiddler, or you could use the Google Analytics Debugger Chrome extension along with Chrome’s JavaScript Console. The idea is to capture the tags that are sent to the Google Analytics server and to analyze them. The problem is that this is a highly manual task. It is OK if you are looking at five pages, but the point of an audit is to look at a large set of pages, if not all the pages. So the easiest way to capture Google Analytics Classic and Google Analytics Universal tags across a large set of pages is by using a web analytics audit tool called Amplytics.
Getting this data will set you up to do the technical portion of your Google Analytics audit. Let’s take a look at what the technical portion entails:
The Technical Google Analytics Audit
The technical portion of a Google Analytics audit deals with checking whether the tracking code on web pages has been implemented correctly. Here are the questions you need to answer in your audit:
Q1: Does each page have the right UA tracking code?
The UA code assigned to your Google Analytics property should match the one that is implemented in the tracking code on web pages. When a tag falls off a page, you’ll see self-referral issues in Google Analytics. Of course, the other big problem is that no visitor activity data will be recorded in analytics for that page! Here’s a screenshot of a UA code as seen in Google Analytics and in Amplytics: 
Q2: Is there more than 1 property where this analytics data is being transmitted?
It is very possible that there may be remnant code from previous installations or even code from third parties on this page. This is typically the case when there are third party plugins installed on the page. For example, Disqus has its own GA tracking code that executes on every page where Disqus is installed. So be aware of third party tracking codes firing and be sure to focus on your own tracking code!
Q3: How many times does the tracking code fire for a page?
With Universal Analytics, events and pageviews are fired separately. So there could be multiple tags fired for the same UA property. Here’s a screenshot of an Amplytics audit for Cheap Caribbean’s page, which shows multiple hit types for the same property: 
Q4: What pages are events, dimensions, and custom metrics firing on?
It isn’t enough to look at the number of times the tag fires. That is child’s play. Here’s where things start getting really interesting. Make a list of all the events, dimensions, and custom metrics that are getting set. Check what pages these are getting fired on. Then ask yourself, does it make sense for the event/dimension/metric to be set on these pages? Here’s an example of an audit of the PacSun site where dimension1 is being set on various pages of the site. 
Q5: Do the tags change if the pages are accessed via a mobile platform or different browser?
Sounds implausible, but it is fairly common for developers to code functionality to fit the resolution needs of various platforms and browsers. This does break or change tags. So it becomes important to audit the tags for major browsers and platforms.
These five major questions should cover the majority of the technical Google Analytics audit. There will be minor variations or additions to the above for each site. Now let’s take a look at the Google Analytics setup itself as a step in this analytics audit.
Google Analytics Setup Audit
The setup audit deals with validation of how your Google Analytics account is setup overall. While some of these areas may be frequented by you or your Google Analytics admin, these are the essential questions you need to answer:
Q1: Do all users have the right level of privileges into Google Analytics?
A very basic question, but it is often overlooked at companies that do not have dedicated Google Analytics administrators. Go one step further and ask the administrators, users, and collaborators whether they really do need access to Google Analytics. Ensure there is at least more than one user who has administrator privileges on the GA account. Last but not least, users can be managed at three levels in Google Analytics. So be sure to check the settings at all levels.
Q2: Are you using the right accounts to link into other Google Accounts?
The list of products that can link into Google Analytics seems to grow each year. As of now, there are 10 products that could be linked. Given that personnel change, it is best to check the account used to link these products and to start using an administrative account that isn’t going away anytime soon to link the products. 
Q3: Are the defined custom dimensions and custom metrics being used?
There are only 20 custom dimensions and metrics available for free accounts to use. So these need to be used judiciously. Remember the technical audit that you did to get a list of all custom dimensions and metrics that were being set? Well, time to pull out that list and check whether the dimensions and metrics defined in this view are even being used in the tracking code. This is important from a usability perspective. Think of your Google Analytics space to be your office. Every once in a while it gets so cluttered that it is impossible to get any work done. Similarly, as priorities and people change, the need for customizations come and go. And for new users, using custom dimensions and metrics can be a hazard if they have no idea whether they are even defined right. Thankfully Google has provided us a way to turn off these customizations without deleting them. So take advantage of that and turn off the customizations not in use.
Q4: Are the view settings correct?
For each active Google Analytics property view, check whether all the settings are correct. A frequently missed update is setting the query parameter for site search appropriately. Such tiny updates are what keeps Google Analytics primed and ready for use. 
Q5: Are filters, goals, and segment definitions correct?
In a data-oriented organization, there is a concept of the single truth for definitions of segments. This is a pivotal step in the maturity of an organization toward embracing web analytics. If your organization is already here, then your job just got easier. Just review the definitions of segments and push them out to users in your organizations to replace. If not, then plan on educating your users about the changes they may need to make to their segments in case of updates or fixes you make to the analytics setup.
One word about filters. These are extremely powerful tools to manipulate data that enters into Google Analytics. So be very circumspect in auditing the definitions of filters for each Google Analytics view.
The above 5 questions cover the majority of the Google Analytics setup sections that need to be audited regularly. There’s only one more area left to audit. And it is possibly the most difficult to investigate. Let’s take a look at auditing marketing channels URLs. 
Marketing Channel Data Audit
The saying goes “Garbage in, garbage out,” meaning if bad data is fed into Google Analytics, you will end up with bad data in your reports. Some of the frequent bad data offenders are marketing channels that drive traffic to your site. Google Analytics works off of attributes that are passed to it as query string parameters in URLs. So paid search, email marketing, and other campaigns can only be effectively tracked if the data they send in their query string parameters is indeed accurate.
My advice to you is to load up URLs used by the various marketing teams into Excel and analyze these for irregularities in the URL structure that might cause the query string parameters to be incorrect.
Then take a peek at the campaign parameters recorded in Google Analytics and validate whether the data is indeed being recorded as desired.
Summary
Google Analytics is an incredibly helpful tool to find actionable insights for your website. However, its usefulness depends on the quality of data being fed into it. And that quality can be controlled by regular audits.
In conducting a Google Analytics audit, there three key areas to review – the setup of tracking code on web pages, the settings in Google Analytics itself, and the marketing channel data being passed into Google Analytics.
