When running a funnel with a group by applied, you may notice your conversion rate increase after applying an event-level filter. For example, if you are analyzing pageviews grouped by country, and you apply an event-level filter to exclude a certain country, your conversion rate may increase.
This has to do with the way Heap categorizes users who could belong to multiple groups in the group by. Following our example, if one user completed this funnel three times in three different countries (let’s say the USA, Canada, and Mexico) when you run the funnel without the event-level filter excluding one of those three countries, the user will be grouped into the country where they did the event first (let’s say USA).
However, if you apply an event-level filter to exclude users from the USA, then the user will be added to either the Canada or Mexico group, thus increasing the conversion rate.
For more information about funnel analysis, see our Funnel analysis overview guide.