A dimension is a data attribute and has a non-quantitative value. A metric is paired with a dimension and has a quantitative value. For example, a page title is a dimension, and a page view is a metric.
When you look at any core report in Analytics, a dimension will appear in the first column. In other columns, usually will be metrics. Sometimes, the report will also have nested dimensions. For example, the page report has a dimension page title, metrics page views, unique page views, entries, bounce rate, and exit rate. It also has nested dimensions, such as, channel, device type, device model.
About event and session scope
Dimensions and metrics belong to an event or a session scope. An event is an individual interaction during a session. A session includes all events during an entire visit. We can illustrate the difference between them in the following way.
Now, let’s see a few examples.
Event scope
Here are some samples of dimensions from an event scope:
- Page URL: The URL of the page on which the event was tracked.
- Search keyword: A query that a visitor typed in the search on your website.
- Goal name: The name of a goal set for your website.
Here are some samples of metrics from an event scope:
- Page view: The total number of times a page was visited.
- Searches: The total number of searches on your website.
- Goal conversions: The total number of conversions for goals.
Session scope
Here are some samples of dimensions from a session scope:
- Campaign: A campaign from which a visitor came to the website and started a session.
- Device type: The type of the device used by a visitor during the session.
- Session entry URL: The URL of the page from which the session has started.
Here are some samples of metrics from a session scope:
- Sessions: The total number of sessions.
- Average session time: An average time of session duration.
- Bounce rate: The percentage of sessions during which visitors viewed only one page and didn’t continue to another page view, goal conversion, or e-commerce conversion.
How a report is calculated
Now, let’s take a closer look at how data is calculated for a report. This will help you better understand dimensions, metrics, and scopes.
Here’s an example of events that happened on the Clear Bank website.
| Event type | Page URL (path) | Device type | Goal name | Goal revenue | |
|---|---|---|---|---|---|
| Event 1 | Goal conversion | /product-tour/ | Desktop | App signup | $50 |
| Event 2 | Site search | /help/ | Mobile | – | – |
| Event 3 | Page view | /blog/ | Mobile | – | – |
| Event 4 | Goal conversion | /blog/ | Desktop | Newsletter signup | $5 |
Everything that you can see in the header row of the example is a dimension — event type, page URL (path), device type, goal name, and goal revenue.
A metric is something that can be calculated for a dimension. Let’s see two examples.
| Page URL (path) | Events | Goal conversion | Sum of goal revenue |
|---|---|---|---|
| /product-tour/ | 1 | 1 | $50 |
| /help/ | 1 | 0 | 0 |
| /blog/ | 2 | 1 | $5 |
In this case, a page URL (path) is a dimension, and events, a goal conversion, and a sum of goal revenue are metrics.
| Device type | Events | Goal conversion | Sum of goal revenue |
|---|---|---|---|
| Desktop | 2 | 2 | $55 |
| Mobile | 2 | 0 | 0 |
In this case, a device type is a dimension, and events, a goal conversion, and a sum of goal revenue are metrics.
Some metrics are simple counters, others are calculated based on dimension values. For the latter, you need to convert a dimension to a metric. Also, when you use a metric calculated from a session dimension, you can’t pair it with an event dimension. See this article to learn more about it.