I have a dataset with all the calls to an emergency service in a period of time.
I have information about the time (in seconds) that it took to respond to that call and the area where the emergency took place.
The emergency service admitted that some records have been recorded incorrectly. For example, there are response times that last for 24 hours or just 0 seconds. This mistakes are caused by human errors but they can compromise my analysis.
I want to find out the average response time in each area but, as there are a lot of outliers, I want to use the trimmed mean for each area.
My question is: is there any other way of excluding the outliers for the whole dataset instead of doing it for each area?