Dimensions vs Metrics: What’s the difference?
Google Analytics has two kinds of data: Dimensions and Metrics. So what’s the difference, and when do we see them?
Dimensions are the kinds of things you would see in the rows of a Google Analytics report. For example, language is a dimension — you can even see a whole report with rows and rows of language preferences. Browser preference is a dimension. Campaign is a dimension. “Page” (aka request URI) is a dimension. You can find all those things as the titles of rows in Google Analytics reports.
Metrics, on the other hand, are the numbers that usually populate those rows. So you might have a City report, and it gives you rows with the names of cities that visitors came from, but it also gives you metrics: how many visits per city, what the average time on site per city was, what the bounce rate per city was, and so forth.
OK, now for some examples. In the accompanying screenshot — taken from the custom report capability in GA – I’ve opened up the metrics for site usage, up top in blue. So we see bounces, entrances, exits, new visits, etc. All things that you would expect to see in the reports (in the boxes, or in the bars as measurements of goodness/badness.)
Below that, in green, you can see how I’ve opened up the Content dimension so that you can see the specific dimensions available to you there. Notice how nicely they fall into that definition: Page Title, Hostname, Page — all things that you would expect to be the headers of rows in a report. So you might see a report of page titles, and each row would have a different page title, and the report might tell us bounce rate, entrances or entrance rate, exits, etc.
But wait! You are saying, what about that new visits up there in metrics? After all, we have a report in Googel Analtyics, in the Visitors section, called Visitor type, and it shows us New vs Returning visitors. Aren’t they the names of rows? So doesn’t the definition fall apart?
Well, no. If you look carefully, there is a metric called new visits, a metric called % new visits, and a dimension called visitor type.
Many thanks to Jonathan Weber for his help with this one.