Analytics Data That Will Expire After May 25

An email that was easy to skip

Among the dozens of privacy emails arriving this month, Google has sent one to Analytics users about a new setting called data retention.

From May 25, it decides how long Analytics keeps the detailed data behind your reports. Anything older than the period chosen will be deleted automatically, on a rolling monthly basis.

If nobody changes it, the period is 26 months.

Nothing breaks on the day, and the reports you open most often will look the same. The question is what you might want from older data later, and whether it will still be there.

What the setting deletes

Analytics holds your data in two forms. One is summarised: totals of visits, pages and goals for each day, which is what most standard reports are built from.

The other is the detail underneath: each visitor's identifier, each visit and each action, linked together. Google calls this user-level and event-level data, and it includes anything tied to cookies, User-ID or advertising identifiers.

The retention setting applies to the detail. Google says reports based on aggregated data are not affected, so last year's monthly totals will not vanish.

Where the difference shows

• Standard reports on old dates, which should look as they do now.
• Segments applied to dates older than the period.
• Custom reports combining dimensions in new ways for old dates.
• The User Explorer report, which lists individual visitors.
• Long comparisons slicing several years by device or source.

The second is the one a small business would miss. Segments, such as phone visitors who reached the contact page, draw on the detailed data, so once it is deleted, new questions about old dates may go unanswered.

Choosing a period

The choices are 14, 26, 38 or 50 months, or "Do not automatically expire", which keeps the detail indefinitely.

Choose by the longest comparison you would ever make in detail. A business comparing this spring with last spring is covered by 26 months.

One that compares three or four seasons, or wants a detailed before and after around a redesign, may want 38 or 50.

There is also a switch called reset on new activity. When it is on, a returning visitor's clock restarts each time they come back, so only visitors who have gone quiet age out.

The privacy side

The setting arrives with the European privacy rules that apply from May 25, and their direction is plain: keep information about individuals only as long as there is a reason to.

Canadian privacy law has said much the same for years. Personal information should be kept only as long as the purpose it was collected for requires, and analytics identifiers can count.

Keeping it indefinitely holds the most detail about the most people for the longest time. Some businesses have a reason for that; most do not.

Whatever you choose, check that your privacy policy does not promise something different.

A worked example

A kayak rental and tour company on the coast does nearly all its business between May and September. Each fall the owner compares the summer's online bookings, by source and device, with previous summers.

Those comparisons use segments. With the default of 26 months, most of the detail for the summer of 2016 would be gone by the time this year's comparison was run, and three summers would shrink to two.

This week, whoever looks after the company's Analytics ran the segmented summer figures for 2015, 2016 and 2017 and exported them to a spreadsheet, so those comparisons survive whatever happens to the detail.

They then set retention to 38 months, turned reset on new activity on, and wrote down why. Visitors who come back each summer on the same device keep their history; one-off visitors from years ago age out.

What to record first

Since the summary reports survive, the job is to save the detailed answers you might want later, while the detail still exists.

Run the segments you rely on, such as phone against desktop, or visitors who reached the contact page, across every year you have. Export them by month to a spreadsheet you control.

Note the current setting and the date you changed it. An annotation in Analytics on May 25 will tell anyone reading a report next year why older segments stop where they do.

An hour spent now answers a question nobody could answer two years from now.

Who should change it

The setting is under Admin, in the property column, under Tracking Info and then Data Retention. Changing it needs edit permission on the property.

Many owners do not have that on their own account, because whoever set up Analytics kept it. If that is your web company, ask what they chose, or whether they chose anything, and ask for the answer in writing.

The setting belongs to each property, so a business with several sites, or an old property still quietly collecting data, has more than one to check.

What the setting does not do

It does not stop or change data collection. Tracking, goals and filters carry on exactly as before, and new visits are recorded as usual.

It does not touch the totals in your standard reports, which are the part most owners actually read.

And on its own it settles nothing else the new rules raise: whether visitors' IP addresses are shortened before they are stored, whether consent is needed, or the terms under which Google processes the data. Those are separate questions.

The counter-case

For plenty of small businesses, the default will cost nothing they would notice.

A business that only ever reads monthly totals keeps those. A site with less than two years of data has nothing old enough to lose yet.

And shorter retention means less information about individuals held on your behalf, which is no bad thing.

But the choice should be made by somebody, on purpose, with anything worth keeping saved first. Export what you would miss, then choose a period with a reason behind it.

Before the 25th

1. Open the Data Retention setting for each property.
2. Note what it says today.
3. List the comparisons you actually make.
4. Export the segmented figures for every year.
5. Choose a period that covers those comparisons.
6. Decide on reset on new activity.
7. Write down the choice and the reason.

Step four is the one that cannot wait. The setting can be changed at any time, but detail that has been deleted cannot be exported after the fact.

Comparing old figures with new ones has a trap of its own, covered in when Easter moves, comparisons break.

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