How to compare periods of time in Google Analytics


How do you compare different time periods in Google Analytics? What time periods should you compare? And how do you avoid misleading metrics?
Hold your horses: First, let’s talk about why comparing time periods in GA is important. Comparing time periods allows you to see

question and answer framework

By comparing time periods, you can gather the information that matters, analyze it to find patterns or problems, and then take action based on those insights.


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How to compare periods in Google Analytics

compare time periods in ga

Where are all of the important buttons on websites? At the top and to the right.
Open Google Analytics, go to a section such as “Acquisition” and go to the top right. Here you can see the dates it is currently reporting on, most likely the last 7 days. Choose your desired date range: In this example, we’ll look at January 1 to December 31, 2017. Now you are looking at that year. To compare, you check the box next to “Compare periods.” You can choose a custom date range, the previous year, or the previous period.

Not all months have the same number of days, so we recommend comparing to “previous period” to get the most accurate data. Likewise, when comparing periods, remember that web traffic is seasonal. You run different campaigns at different times of year, and people tend to be less active online in the summer and around the holidays. If you want to better understand how traffic performed in a span of months, say Q1 2017, then compare to the same span of months in the previous year.
Note that Google Analytics takes about a day to gather all the data, so we wouldn’t recommend pulling a year-over-year or month-over-month report until a few days into the following year or month.

What time periods should you compare?

To help you get started, here are a few ideas for how you can use Google Analytics’ custom time periods to your advantage:

  • Year-over-year: See how traffic is performing this year compared to last year. Are you growing (hint: you want to be growing).
  • Quarter over quarter: To reach your annual goals, track your progress each quarter. This will allow you to stay on top of those goals that we often forget about until the last minute.
  • Sprint-over-sprint and Month-over-month: We recommend running a “firecheck” on your Google Analytics account every 2 weeks (or every “sprint” if agile project management is your thing). Look at the last 2 weeks versus the 2 weeks prior. Then look at month-over-month. Are your goals tracking? Are there any crazy dips in traffic? Are those dips on purpose or is the data getting lost? Make sure you address any issues immediately

Misleading Metrics to Avoid

We’ve already touched on comparing periods to compare apples to apples, but there is another common tracking pitfall to avoid.

Quick quiz:

Turtle is tracking Whole Whale’s site traffic. She sets the custom date range for June 1 to August 31, and finds that there were 2,000 users.
She isn’t certain that’s correct, so she looks at each month individually and finds that in June there were 1,500 users, in July there were 1,000 users, and in August there were 1,200 users; a total of 3,700. How is this possible?
Google Analytics uses cookies to track unique users over time. So there were 1,500 unique users in June, but many returned in the following months. Overall, there were 2,000 unique computers or people checking out Whole Whale’s site in the summer months. When looking at unique users, pageviews, or similar seasonal goals, be sure to look at the overall time period to get the most accurate numbers.
Bet you didn’t think you’d be doing math when you got to this article, but being aware of how data can be misleading, and knowing the right questions to ask will allow you to find richer insights to inform a more successful digital strategy.
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