GA4: One-Stop Analytics Solution for Data Unification

GA4 is often misunderstood as an upgraded version of Universal Analytics. That is partially correct, but there are some noticeable and vital differences between these tools, with the new data model topping that list. GA4 provides a more comprehensive method for cross-device tracking, providing a single user-journey view of your reports. The ability of GA4 to track users across devices and platforms (independent of any third-party cookies) is one of its most powerful features, focusing on one of the crucial factors in today’s data world, user privacy.

Are you wanting to migrate your Universal Analytics property to GA4 but are not sure if the timeline suffices from an implementation and acquaintance point of view? Of course, we have a solution and can make it all happen in just a few weeks. Choose the plan that works best for you, but do it before it’s too late

Why Cross-Device Tracking is Important

Let’s say a person wakes up in the morning, receives a notification from your app, opens it, and eventually starts some interaction with your business through the mobile app. Then later in the day, they continue browsing your website on their laptop and eventually convert through the mobile site.

Here, Google Analytics 4 plays a vital role over Universal Analytics. GA4 will blend this user journey and enable thorough reporting identity to unify a user’s cross-device interaction points. What does this reporting identity refer to? Let’s dive deep into the details.

How Users Are Tracked In GA4

A reporting identity in GA4 is used to track and measure user engagement and conversion across multiple devices and sessions.

Reporting identity is a fundamental piece of your Google Analytics 4 property. When setting up Google Analytics (GA4), one of the important steps is to select a default reporting identity for gathering data about your users and having it applied to your reports. 

Google Analytics 4 has four methods for identifying visitors to your website, i.e. User ID, Google signals, Device ID, and Modeling to create a single cross-device user journey.

A brief about these methods:

  • User ID

You can track user journeys across devices if you generate your persistent IDs for signed-in users. You must consistently issue IDs to your users to use this identity space, and you must send Analytics the IDs along with the data you transmit. Because it leverages the information you gather to identify your users, User ID is the identity space that is the most accurate.

  • Google Signals

Data from Google-logged-in users is referred to as Google signals. When Google signals data is available, Analytics links the user-submitted event data to the Google accounts of logged-in users who have authorized sharing of this data.

  • Device-ID

The device ID is another identification space that analytics can use. The client ID serves as the source of the device ID’s value on web pages. The device ID is the app instance ID for apps.

  • Modeling

Behavioral data for users who reject Analytics identifiers like cookies is not available. Analytics closes this gap by simulating the behavior of similar users who do accept cookies from the same property.

How Analytics Determines the Reporting Identity

Under the Admin section of the GA4 property, you can choose any of the three Identity Space options to decide how to collect data about your users.

The first option here is Blended. The way it works is if you have a User ID implemented, that one gets the first preference to be your Reporting Identity. If no User ID is collected, Analytics will rely on Google signals if they are available. If neither the User ID nor the Google signals are available, Analytics will use the Device ID. And lastly, Analytics will rely on Modeling if none of the identifiers are available.

The second option is Observed; it is also dependent on the User ID. If no user ID is collected, Analytics will use data from Google signals if it is available. If both are not available, Analytics will use the Device ID.

The last one is Device-based, which only uses the Device ID by ignoring all other methods of collection.

Enabling either of the first two options is recommended because Analytics will search through all three available reporting identities to find the most accurate one and help us unify the user across devices.

In this blog, we will be focusing on the first reporting identity – User ID, since Google recommends that one be the most accurate and reliable one.

User ID For Cross-Device Journey

Now we have an idea of how users are tracked in GA4, let’s get into user ID tracking for user journey stitching. User ID allows you to associate a single user’s persistent ID with engagement data from one or more sessions initiated by one or more devices.

Assume you have a website where users can log in using their credentials. When users browse your website, the system recognizes them as the same user. Even if a user visits your website on multiple devices or interacts across the website and mobile app, GA4 will distinguish this as a single journey.

As previously stated, if a User ID is not available GA4 stitches the user journey via Google signals. And if Google signal is not available, a Device ID is used.

The term “device” refers to first-party cookies. If a visitor clears his or her cookies or begins using a different device, it will be treated as a new device. Google Signals collects information from users who have Google Accounts and have enabled ad personalization. The User ID, on the other hand, is the most precise method of identifying visitors.

What Next?

Once you have implemented User ID and related data from multiple sessions/devices to Google Analytics, your reports will start showing a more unified, comprehensive journey about a user’s behavior with your business.

User Exploration

It will show you how users interact with various devices, and you may notice a decrease in the number of users. The reason for this is that GA4 will begin to recognize multiple devices as belonging to the same user if that user logs in using multiple devices.

However, it is not always the case that users are logged in and browsing the website. The majority of traffic is pseudonymous. For example, in the report below, you can see the different formats of ids collected under the dimension App Instance ID. Some of them like ‘1610690016.1677155193’ are Client IDs (assigned by GA when User IDs are not available) and some like ‘98098’ are actual User IDs.


When you click on the second row of the above report, for example, you can get a detailed overview of this user’s activity on your website, in terms of their interaction and engagement on the website.

Data Comparison with Signed-in Users

One more way to utilize the User ID feature is to create a comparison in any of your GA4 reports. You can quickly determine how many people have signed in and how their behavior is different by comparing all users against logged-in users (with User ID dimension).

Click Add comparison in any GA4 standard report and enter the condition as shown below. In comparison to all users, you will now see the logged-in users’ data on your website/app.

Segment Overlap

Another application of User ID is the ability to observe how users interact with various devices. In the Explore section of your GA4 Reports, select the Segment Overlap technique, you can select two default segments as shown in the screenshot, and create one more segment with the condition ‘Device Category containing Desktop’. Save the segment and add this to the Segment Comparison. Now you can see, as in the below screenshot, that a few users are using multiple devices to log in to websites.


It is critical to note that if you configure the User ID in GA4, it will not be available as a Custom Dimension, by default. However, as a workaround, you can send an additional parameter and register it as a User-scoped Custom Dimension with a different name than the user_id.

Final Thoughts

GA4 is a remarkable upgrade to Universal Analytics that can assist you in providing a more enhanced and effective analysis of your users. It is only available if you have some form of user identification. User ID tracking in Google Analytics 4 is unquestionably superior to Universal Analytics and you do not need to create a separate view for that. Cross-device journey tracking with user ID helps you get more accurate numbers in your reports and a more complete picture of people’s engagement with your website.

We are just 3 months away from Universal Analytics’ sunset. And with such an amazing new tool already available at your discretion, what are you waiting for? Reach out today to achieve the migration in just 1 week, and let our experts acquaint your team with GA4.

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