In this article, we will explore how you can harmonize data across Universal Analytics & Google Analytics 4 to ensure seamless reporting without overlap/double-counting. The reason this is interesting to many marketers is that once you've made the switch from Universal Analytics to Google Analytics 4 reporting, there are likely instances where you would like to retain the option to report on data across both platforms (for instance for year-on-year analysis).

In Funnel, you have the option to connect both Universal Analytics & Google Analytics 4 data sources. If you are interested to learn more about equivalent fields between both systems, you can read this help article.

When you connect your Universal Analytics data source in Funnel it will contain at least two years of historical data (assuming that your Universal Analytics View has been collecting Hits for that long). When you connect your corresponding Google Analytics 4 data source, it will fetch data back to when it first started registering Events. In most cases, this will mean that there will be an overlap in the date ranges between the data sources, as seen in the visualization below:

To ensure that you are not overreporting your metrics, you need to make sure that you only show/export data from one of the data sources for each date. Funnel's recommended option is to create a custom dimension that designates the "stitch date" between the data sources (E.g. use Universal Analytics prior to Jan 1st, 2023, after that use Google Analytics 4).

The reason Funnel recommends this approach is that it is reversible. Six months after Universal Analytics stops processing new data (currently slated for July 1st, 2023), Funnel will no longer be able to retrieve data from the Univeral Analytics API, which means that decisions are "final". With Funnel's proposed approach, you retain the option to change the stitch date at any point as you keep all underlying data in Funnel. When you're inspecting a large data set, it can be difficult to assess the validity of all fields, and you should retain the option to move the stitch date if needed, as shown in the graphic below.

Here you have the option to create 3 different outputs by changing the stitch date, whilst keeping all underlying historical data:

There are 2 main ways that we recommend to map fields between Universal Analytics and Google Analytics 4 (both shown below).

The benefit of this method is that you can see all the logic in one rule, including the date.

The benefit of this method is that if you need to make changes to your starting and end date at a later point, you would only have to update it in one place.

The first step is to create a custom dimension (see example below) where you pick the stitch date in your reporting. In the below case, Google Analytics data prior to March 31st, 2022 is classified as "UA" and data after April 1st, 2022 is classified as "GA4". As mentioned earlier in the article, you can change the date selected at any point by updating the rules in this dimension.

Note: This dimension is used to control all the underlying custom metrics you create between Universal Analytics and Google Analytics 4 and therefore does not need to be part of visualizations or export schemas. This stitch date logic can also be implemented on the individual metric level, but since that will require you to replicate the date pattern on each metric we recommend that you use a single dimension for the same purpose instead.

The next step is to create a harmonized metric across Universal Analytics & Google Analytics 4. If you want to get a full breakdown of equivalent fields between Universal Analytics & Google Analytics 4, you can see our separate help article here.

In the below example, we have built a custom metric for Sessions for Google Analytics. Utilizing the dimension, we want Sessions from Universal Analytics to be used when matched to "UA". Similarly, we want Sessions from Google Analytics 4 to be used when matched to "GA4".
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Note: The logic shown here is not unique to Sessions, and can be used for all metrics where there is an equivalent field in both Universal Analytics & Google Analytics 4. Metrics are sometimes named the same in both Universal Analytics & Google Analytics 4 (as in the case with Sessions), make sure that you pick the correct metric for each platform when building your rules.

Using the metric created above, you get the following output in Data Explorer where Sessions from Universal Analytics are used up until March 31st, 2022, and Sessions from Google Analytics 4 are used from April 1st, 2022:

When exporting your data outside of Funnel, the logic works the same way. In the below Time Series chart, you can see the custom GA Sessions metric created above in a line chart:

Or in a Bar chart:

If you have any questions about the contents of this article or need support in completing your migration from Universal Analytics to Google Analytics 4 reporting, please reach out to your customer success partner at Funnel.