Google Analytics dimensions and metrics explained
What is a “dimension” in Google Analytics?
A “dimension” is an attribute of your data, you can think of them as the “categories” that your users fall into. For example, if a 25-year-old man in Germany accesses your site from a Facebook ad on his smartphone, the dimension attributes would be as follows:
- Gender: Male
- Age: 25-34
- Location: Germany
- Source/Medium: Facebook/paid_social
- Device Category: Mobile
Dimensions are the characteristics of the visitors on your site, they tell you information about your customer’s age and gender, plus what device they’re using and where they are in the world.
A few other examples of dimensions in Google Analytics are:
- Language
- Page
- Title
- Operating System
- Campaign
- Keyword
What is a “metric” in Google Analytics?
A metric is a quantitative measurement that tells you the number of people within each dimension. For example, a dimension will let you know which country your visitor came from, but a metric will let you know how many other people also came from that country, plus what that country’s average session duration is or its bounce rate.
A few other examples of metrics in Google Analytics are:
- Sessions
- Users
- Pages per user
- Average time on page
- Goal completions
Metrics are helpful for analysing your data, but they’re obsolete without dimensions to compare your data against.
What is the difference between a dimension and a metric in Google Analytics?
Simply put, dimensions are the titles of the rows in your Google Analytics reports, whereas metrics are the numbers that populate these rows.
Think of dimensions as the characteristics of your customers and metrics as the measures of those attributes. For example, “United Kingdom” is a location dimension, whereas the bounce rate and revenue of this location are your metrics. Or, another example, your website homepage is the dimension, with average time on page and sessions being the metrics.
Which default traffic source dimensions does Google Analytics report for each website visitor?
When reporting on website visits, Google Analytics will tell you the source and medium of your users by default.
The source is the channel through which your visitor found you, so whether they came to your site through Google, Facebook or Bing.
The medium lets you know what type of traffic this is, for example, it could be paid, organic or referral.
The majority of dimensions are tagged automatically by Google, but if you want to track a specific campaign – an email marketing campaign, for example – you’ll need to use UTM tracking to let Google know where your users are coming from.
A few other examples of source/medium dimensions are:
- bing/organic
- google/cpc
- google/organic
- (direct)/(none)
Predefined and custom dimensions
Predefined dimensions are available in Google Analytics as standard and can be used straight away when creating reports. Predefined dimensions are things like location, age, gender and the device category of your users.
Alternatively, custom dimensions are defined by you – usually with data that’s not readily available in Google Analytics. For example, you can import additional data such as CRM data, logged in user data (that’s non personally identifiable) or phone call data to create a custom dimension. Custom dimensions give you better control over your reports and allow you to analyse the values that matter to you, whatever they may be.
What is a primary dimension in Google Analytics?
Google Analytics chooses a default primary dimension for any report that you run. For example, in the acquisition overview report, Google automatically selects the default channel grouping for you as the primary dimension. Whereas in the e-commerce overview report, the product dimension is selected.
What is a secondary dimension in Google Analytics?
A secondary dimension adds another dimension (in addition to the primary dimension) within the same table to add more granular data to your report. This can be really useful when trying to answer more specific questions about your data or user behaviour.
For example, if you wanted to understand which channels people from England were accessing your site from, you would start by selecting England as the primary location dimension. You could then add a secondary dimension of source/medium to see which channels they’re coming from.
Custom dimension configuration values
Every custom dimension that you create in Google Analytics has got five properties (also called configuration values):
- Name - this determines how the custom dimension will appear in your GA reports
- Index - this is a number used by GA to identify and differentiate your custom dimensions from one another. No two custom dimensions can have the same index number
- Scope - this determines the hits that will be associated with the value of the custom dimension
- Last changed - this is a number used by GA to identify and differentiate your custom dimensions from one another. No two custom dimensions can have the same index number
- State - this identifies the status of the custom dimension, whether active or inactive
What are the four scope levels available for dimensions in Google Analytics
When a custom dimension is processed by Google Analytics, the scope determines to which hits a particular custom dimension will be applied.
There are four scope levels that you can set for your custom dimensions, these are:
- Hit level dimensions – the value of the custom dimension applies to the single hit for which it has been set. Some examples of common hits are pageviews, screenviews, events or transactions. Google Analytics will calculate and send the value of the custom dimension for each hit.
- Session level dimensions – a group of hits recorded for a user within a given timeframe, be that over one day, a few weeks or a month. A session expires after 30 minutes of inactivity from your user. Google Analytics will calculate and send the value of the custom dimension only once per session.
- User level dimensions – a unique client ID set by a Google Analytics cookie when a browser first loads your site. These unique IDs cannot be identified across devices and exist only on the browser where the cookie was set. Google Analytics will calculate and send the value of the custom dimension only once per user.
- Product level dimensions – the value of the custom dimension applies to the product for which it has been set. Product level scope requires you to have set up enhanced e-commerce tracking on your site. Google Analytics will calculate and send the value of the custom dimension only once per product.
Predefined and custom metrics
A predefined metric is one that’s readily available in Google Analytics. Google provides over 200 predefined metrics, such as sessions, page views, bounce rate, click-through rate, transactions and average time on page.
Alternatively, if you want to measure a dimension that isn’t created in GA by default – such as phone calls or CRM data – you can create a custom metric that pulls in data from an external source to track the values that matter to you. For example, if your company tracks phone calls back to the keyword that created them, you could set up ‘phone calls’ as a custom metric, splitting out your data by the predefined dimension of ‘keyword’.
Custom metrics can be used alongside both predefined dimensions and custom dimensions in your Google Analytics reports.
Custom metric configuration values
Each custom metric created in GA has got eight properties (also known as configuration values). These are:
- Name – a descriptive, unique name that determines how the custom metric will appear in your GA reports
- Index – a number that GA uses to identify and differentiate between your custom metrics. No two custom metrics can have the same index number
- Scope – determines the hits that will be associated with the value of the custom metric
- Formatting type – determines how the custom metric will be displayed in reports, for example, currency (decimal number), time (number of seconds) or integer (whole number)
- Last changed – the date when the custom metric was created or last modified
- State – the current status of the custom metric, either active or inactive
- Minimum value – the smallest value of a custom metric that should be calculated and shown in your reports
- Maximum value – the largest value of a custom metric that should be calculated and shown in your reports
What scope applies to custom metrics?
Every custom metric that you create in GA can have each of the following two scopes:
- Hit – the value of the custom metric is only applied to the hit with which the value was sent. Google Analytics will calculate and send the value for each hit.
- Product – the value of the custom metric is only applied to the product with which the value was set. Product level scope requires enhanced e-commerce tracking to be enabled on your website. Google Analytics will calculate and send the value for each product.
Learn more about Google Analytics reports
If you’d like to learn more about how to create meaningful reports in Google Analytics, try our Standard and Advanced Google Analytics courses. Led by industry experts, this course will teach you how to use reports to improve your digital strategy and meet your online business goals. Alternatively view our full range of Analytics and Optimisation courses.
