What are Dimensions and Metrics?

Frequently, I encounter confusion when I walk someone through building custom reports in Google Analytics (GA) for the first time. I’ve noticed that many times, the problem is confusion caused by dimensions and metrics. The lack of understanding makes it difficult to define a report clearly.

Without the understanding of these two fundamental pieces of analytics, it is difficult to get any real value out of your analytics tool.

There are several resources that describe the differences and relationships between metrics and dimensions. I suggest reading the blog posts below to begin your education:

Web Analytics 101, Avinash Kaushik 

Understanding the Building Blocks of Your Reports, Google Analytics

To assist you even further, I want to share my method for understanding and using dimensions and metrics in my web analytics practices.

Dimensions & Metrics

Dimensions, in analytics,  describe the characteristics of your visitors. Examples include:

Where the visitor came from

  • Source/Medium
  • Ad Campaign
  • Keyword Search

What the visitor did while browsing the site

  • Landing Page
  • Exit Page
  • Page Depth

When the visitor was on the site

  • Date
  • Day of the Week
  • Time of Day

Attributes of the visitor

  • Location
  • Browser
  • Device

Actions the visitor completed on the site

  • Transaction
  • Product
  • Affiliation

Dimensions usually define the rows in a report. You can think of them, as you might think about a database of customers. The rows are initially defined by the customer name or ID. In the table below, Customers 1 – 5 are the dimensions.

The metrics are the attributes related to those customers, displayed in the columns — Address, City, State, Phone, and Email.

Example Customer Database

Metrics in GA are similar in that they describe attributes of the dimensions. However, given that it’s an analytics tool, metrics provide the quantitative measurements of the chosen dimension, represented in sums or ratios.

Metrics include information such as:

  • # of Visits
  • # of Unique Visits
  • Bounce Rate
  • Conversion Rate
  • Time on Page
  • $ Value
  • % New Visits
  • Avg. Visit Duration
  • …and many more.

To provide additional context, I’ll explore the process of choosing the appropriate dimensions and metrics to build custom reports to answer simple business questions. Below, I provide three example questions. In each question, I’ve highlighted the part of the question that defines the dimension you should use.

Notice that in each question, the subject of the sentence is the dimension you’re measuring. Once you understand that, it’s only a matter of deciding what attributes are important to measure in order to answer your question.

Three Examples

Q1: Which pages on my web site perform the best?

Page is the primary dimension when answering the question above. Therefore, I built the report to include page details as the dimensions and performance metrics to tell me how my site’s pages are performing. Suggested dimensions and metrics are listed below, in addition to a link to the custom report that you can use in your own reporting.

Dimensions

  • Page Title
  • Page (Secondary dimension)

Metrics

  • Unique Visitors
  • Bounce Rate
  • Avg. Time on Page
  • Goal Conversion Rate

Link to custom report >>

Q2: Which search engines send the most valuable visitors to my site?

Search engines are the primary dimension, which are reported as Sources in GA. Again, I’ve listed the suggested dimensions and metrics below, with a link to the custom report. This report requires an additional step in order to view only the search engine/organic sources.

Dimensions

  • Sources
  • Keyword (Secondary dimension to provide more insight into the intent of the visitor)

*Filtered to only include search engine/organic sources

Metrics

  • Unique Visitors
  • Bounce Rate
  • Avg. Time on Page
  • Goal Conversion Rate

Link to custom report >>

*Make sure to apply the Organic Segment to the report, to filter out all sources, other than search engines. If you’re not familiar with Segments, refer to my recent post on Google’s new custom segments.

Q3: What country are my converters from?

Country is the primary dimension in this example. A report with the dimensions and metrics listed below will provide insight into where visitors who convert are located, so you can focus your efforts by location. I suggest focusing on the areas that drive the highest Goal Conversion Rate.  Once you’ve imported the custom report, sort by conversion rate and take note of the areas with the highest conversion.

Dimensions

  • Country / Territory
  • City (Secondary dimension to dig deeper into the location of your visitors)

Metrics

  • Unique Visitors
  • Bounce Rate
  • Pages / Visit
  • Goal Conversion Rate

Link to custom report >>

There are additional, more involved rules for metrics and dimensions, but I hope that my explanation and examples have provided a basic understanding of these important GA components. While it’s necessary to understand these components for other GA uses, I find it especially important when using Custom Reports and in my opinion Custom Reports are one of the most powerful tools in GA.

For more on Custom Reports, visit Google Analytics’ resource page.