If your bounce rate is close to zero, Analytics is probably installed twice and counting each page view double. Find every copy of the code, keep one, and note the dates so older reports are read with care.

A report that looks too good

The monthly report arrives and the numbers look wonderful. Page views have doubled, visitors read more pages each, and the bounce rate, the share who leave after one page, has fallen almost to nothing.

Nothing about the business explains it. No campaign, no new content, no mention in the local paper.

The likeliest explanation is dull: the Analytics code is on each page twice, and every page view is being counted two times.

It is a common fault, and it quietly makes every report since it began unreliable.

Why the bounce rate collapses

A bounce is a visit that records only one interaction: someone lands on a page and leaves without doing anything Analytics can see.

With two copies of the code, the first page view sends two hits. Analytics sees two interactions in the visit, so no visit counts as a bounce, even when the visitor left at once.

Page views double for the same reason, and pages per visit with them. Visits and visitors often stay roughly right, which is why the fault survives: the headline number looks normal.

How the second copy gets there

The third catches sites that moved to Google Tag Manager carefully but not completely. The tag goes into the container, and the code pasted into the theme years earlier stays where it was.

Signs worth checking

A bounce rate close to zero across a whole site is almost always this fault. Real sites have some visitors who look at one page and leave.

A sudden step in page views or bounce rate on one date, with no matching change in visits, points to the day a second copy went in.

If pages per visit have roughly doubled, that is the same fault seen from another side.

Look at the long view. A year of data, shown by month, makes the step obvious.

Finding every copy

Open a page of the site in a browser, view the page source, and search for UA-, the start of every Universal Analytics tracking ID. Each appearance is a candidate.

Search as well for analytics.js and ga.js, the file names of the current and the older Analytics code, and for GTM-, which marks Google Tag Manager.

Tags added through Tag Manager never appear in the page source, so check inside the container too. Tag Assistant, a free Chrome extension from Google, lists the Google tags on a page and warns when Analytics appears more than once.

Then open the Real-Time report and load a single page yourself. If one page load shows as two page views, the problem is confirmed.

A worked example

A private investigation firm with two licensed investigators and an office manager had its site rebuilt last autumn on a new WordPress theme.

The theme had a setting for the Analytics tracking ID, and the developer filled it in. The old site's Analytics plugin was still installed and active, adding its own copy to every page.

The office manager prepares a monthly summary for the partners. From the launch month on, page views doubled and the bounce rate fell almost to nothing, and the partners took it as proof the new site was working.

This spring a partner asked why enquiries had not moved to match, and the office manager opened the page source.

The plugin came out, leaving the theme's copy. An annotation in Analytics marks the date, and the summary now notes that page views and bounce rate from launch to fix cannot be compared with anything else.

Visits and visitors were unaffected, so the year's main trend still stood.

Keeping one, deliberately

Choose one method and remove the others. For most small sites that is either a single plugin or Google Tag Manager, whichever the person maintaining the site prefers to work with.

Write down which one it is, wherever the site's logins and notes are kept. The next developer, or the next theme, then has a reason not to add another.

Check again after any redesign, theme change or new plugin, since that is when second copies arrive.

A second ID that is not yours

Sometimes the second copy carries a different tracking ID: an old account set up by a previous developer, or an agency's account from a past campaign.

That does not double your figures, but it means another account is still collecting your visitor data, and whoever holds it can read it.

Find out whose account it is. If nobody at the business can sign in to it, remove the code, and make sure the account you keep is owned by the business.

What to do about the old reports

Past data cannot be corrected. Page views and bounce rates recorded while two copies ran stay inflated.

Add an annotation for the day the second copy arrived, if you can find it, and the day it was removed. Anyone reading the reports later will see why the line jumps.

Compare like with like: visits and visitors across the whole period, page views and bounce rate only within the clean stretches.

And treat any decision made on the inflated figures as worth revisiting, especially a redesign judged a success on bounce rate alone.

The counter-case

Not every low bounce rate is a fault. A site whose visitors genuinely click through several pages, or one that records events such as video plays, can show a low rate honestly.

Some setups also send data to two accounts on purpose, the business's own and an agency's, using two different IDs. That is legitimate when everyone knows about it.

But a bounce rate close to zero that arrived suddenly on one date is a duplicate until proven otherwise. Find every copy and keep one.

The check

  1. Look at a year of bounce rate by month.
  2. View the page source and search for UA-.
  3. Check Tag Manager for an Analytics tag.
  4. Run Tag Assistant on the home page.
  5. Remove every copy but one.
  6. Annotate both dates in Analytics.
  7. Write down how Analytics is installed.

Step seven is what stops it happening again, since second copies arrive when someone new adds tracking without knowing it is already there.

Getting clean figures from printed pieces as well is covered in campaign links on printed materials.

Frequently asked questions

Why would my bounce rate be close to zero?

Usually because the Analytics code is on each page twice. Every page view sends two hits, so no visit looks like a single-page visit, even when the visitor left at once.

Does duplicate code change visitor numbers too?

Often visits and visitors stay roughly right while page views double and the bounce rate collapses. If the copies are different versions of the code, visitor counts can be wrong too.

How do I find every copy of the code?

View the page source and search for UA-, analytics.js, ga.js and GTM-, check inside Google Tag Manager, and run Google's Tag Assistant extension, which warns about duplicates.

How does a second copy get added?

A theme setting and a plugin both adding it, Tag Manager added without removing the old code, or a redesign that kept the old snippet. Each step seemed reasonable.

Can the inflated old data be fixed?

No. Annotate the dates the duplicate started and ended, compare visits and visitors across the whole period, and compare page views and bounce rate only within clean stretches.

What if the second copy has another ID?

Then another account is still collecting your visitor data. Find out whose it is, remove the code if nobody at the business controls it, and keep the account you own.

West Coast Media Solutions Inc. provides web design, web development, hosting, digital marketing, and business consulting to organisations across Canada, drawing on more than twenty-five years in the field.

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