Hi question about user dimensions in GB What happens when a

Question

Hi question about user dimensions in GB What happens when a dimension changes its value for a given identifier Let s say I use `anonymous id` based on device id as identifier and have a dimension `visitor type` which can have the values new returning or customer The dimension first has the value new but on a later visit it will be returning because the `anonymous id` was recognized So the user becomes part of the experiment with `visitor type` = new and returns and then sees the experiment but now as `visitor type` = returning How does GB deal with this when I segment the experiment result data by `visitor type`

helpful-application-7107 · Answer

Great question This is definitely a blind spot in the app Because `timestamp` isn t a required field in the User Dimension definition we have to use some arbitrary rule making to select one user dimension per user right now we just use `MAX` On your end the best way to handle this would be to define your User Dimension using <https docs growthbook io app metrics sql templates|SQL Template variables > where you define your user dimension yourself to get the latest record per user that has a `timestamp lt startDate ` so that you can ensure all dimensions are pre experiment best for bias

helpful-application-7107 · Answer

You could do something like the following ```WITH visitor types AS SELECT anonymous id visitor type ROW NUMBER OVER PARTITION BY anonymous id ORDER BY timestamp DESC AS rn FROM dim table WHERE timestamp gt DATE SUB startDate INTERVAL 7 DAY AND timestamp lt startDate SELECT anonymous id visitor type FROM visitor types WHERE rn = 1 ```

prehistoric-beard-84272 · Answer

Thank you Luke I ll try that