Google Analytics 4, also known as GA4, is a new version of Google Analytics. A major difference many website owners and web marketers notice is its sole reliance on last click attribution. It results in unexpected traffic sources shown for meaningful conversions such as purchases that happen later in the funnel.
The main reason for the changed behavior compared to the previous Google Analytics version now called Universal Analytics is that GA4 has been designed as mobile-first solution, adapted for tracking Android apps. However, GA4 offers a way for websites to signal what campaign should be used for reporting future conversions.
The solution is buried deep in the GA4 attribution manual, however is fairly simple: send a first_open conversion event. This event would tell GA4 that the current campaign source (campaign source by the last click/last engagement attribution at a time of the event) should be the user acquisition source. This would make GA4 to attribute all future events happening in the next year to that campaign, effectively implementing a first touch / first click attribution.
This may not be a complete solution for first touch attribution however.
While Google Analytics 4 will be using that campaign when it knows who the customer is, many of the times it won't. For example, a customer could be visiting the website from a different device, or Google Analytics cookies might have expired.
For some applications it may be practical to use Google Analytics 4 User-Id to signal to Google identity of the customer currently interacting with the website so that GA4 could use user attribution as described before to attribute all conversions.
Able Customer Data Platform offers a more wholistic solution to Google Analytics 4 first click attribution.
It records Google Analytics Client Id, as well as many other attribution details when a visitor first visits the website. Then, when a conversions such as purchases happen it attributes them to the original visitor using a personal identifier such as an e-mail and sends the conversion to Google Analytics API attributed to the original Client Id. In addition to solving first click attribution, it allows to track 'offline' conversions such as successful payments or closed deals that happen outside of the browser session.