Avoid Closed Funnels in GA4 for Reliable Funnel Reporting

Don't use closed funnels in GA4 because the reliability of funnel reports is heavily dependent on all relevant events firing correctly and in the correct order.

Conventional wisdom dictates that you make a funnel open or closed based on whether users follow a linear path or are required to complete all steps in the correct order.

But in the case of GA4, you should always make your funnel open as the reliability of funnel reports heavily depends on all relevant events firing correctly and in the correct order.

For example, in GA4, the 'Purchase journey' report is modelled as a closed funnel by default, which makes it unreliable.

Since the purchase journey report in GA4 is a closed funnel, a user must start at the "Session Start" step and successfully navigate each subsequent step in order to be included in the funnel analysis.

Suppose a user skips any of these steps or enters the funnel at a midpoint (such as 'Begin Checkout'). In that case, they are not included in the funnel analysis.

There could also be cases where the 'session_start' event or some other event which is part of the purchase funnel fails to fire. In that case, users associated with such sessions would be excluded entirely.

In a closed funnel, users are either included entirely or excluded entirely.

There's no concept of being "partially included" for some steps and excluded for others.

So, users who skip the initial steps (like viewing products or adding items to the cart) and jump straight to checkout won't be included, even if they complete the purchase.

Similarly, if any event in the predefined sequence fails to fire for some technical reason, the user's journey is considered incomplete, and they are excluded from the funnel analysis, even if they complete a purchase.

This provides an incomplete picture of the overall purchase journey, making the purchase journey report very unreliable.

For the same reason, you should also use an 'open funnel' for the checkout journey.