Google Analytics is not tracking properly. I need help diagnosing the issue

Question

About two weeks ago, the bounce rate for pages on my sight dropped drastically. We went from an average of 70%-80% bounce a page to 2%-20%. It's an absolutely drastic change overnight. While I'd love to take credit for it, this seems wrong. A few things are tipping me off:

1. Despite the bounce rate being so low and pages/session being so high, duration per session is tanking. Getting things like 3.75 pages/session with a duration of fewer than 10 seconds.
2. Pageviews are often near double the Unique Pageviews count

My fear is that for some reason the page tracking is triggering twice per page. Is this possible? And is there a better way to confirm it. I tried running an experiment with Google Optimize and Google Tag Manager and that coincides with when this data change happened. I've disabled both but the data remained the same.

Any insight would be greatly appreciated.

Answer 1

Not only is it possible, it happens fairly often. I would install the Chrome extension called GA Tracking Code Debugger (https://chrome.google.com/webstore/detail/google-analytics-debugger/jnkmfdileelhofjcijamephohjechhna?hl=en) and have it run while a page of the site loads. Here's a brief tutorial, but basically if you see two pageview events logged, then that's the culprit.

As for stopping this from happening if indeed it is, I bet you that a GA tag was inadvertently added in GTM when you were testing it out. Either remove the GA code snippet from the template for your webpages or remove the code individually from the webpages' source codes themselves or by turning off the tool in your CMS that controls your GA (depends on how you added it) OR deactivate the GA tag in GTM and republish the GTM container. Feel free to comment with additional info or questions.