The steady increase in mobile use over the last years has introduced some new challenges for web analytics. It’s not just about mismatches in the tracking model (the concept of sessions is even more absurd for apps than it is for desktop browsing), but about something more fundamental, more basic. Think about it: if a visitor visits the website using a mobile device, there’s a significant chance of them losing internet connectivity and going unintentionally offline.
Here we are again, revisiting an old theme. When using Google Tag Manager, we often want to send the contents of the same tag to multiple Universal Analytics properties. With on-page GA, this used to be quite simple, as all you had to do was create a new tracker and then just remember to run the ga('trackerName.send'...) commands to all the trackers (or you could use my duplicator plugin). With GTM, your options are more limited, since Google Tag Manager abstracts the tracker object, giving you far fewer tools to work with.
One of the things I’ve recommended from the get-go is to always send the Client ID to Google Analytics with your users’ hits. This is very useful for adding a level of granularity to your tracking. At first, I recommended using an Event tag to do this. Then I modified my approach a little so that you could send it with your initial Page View (thus not inflating your hit counts).
First of all, I’m sorry about the title. I should really stop throwing the word “simple” around, since people always tell me that the stuff I claim to be easy and straightforward is rarely so. But since this is my blog, I reserve the right to use whatever stupid and misleading terminology I want. I maintain that what follows IS quite simple, especially when considering the amount of complexity it reduces in your Universal Analytics setup.