Custom visuals: applying filters to just one measure

[emmasaunders]

Hello

I am creating a histogram custom visual. The idea is that two histograms will be overlaid: the population data will show at the back, and sample data (which is optional) will be overlaid in colour. The point is to be able to compare the shape of the distributions, even though the maximum frequencies will be different (since the sample is a subset of the population).

At the moment I intend to have two measures (one optional) and one category in dataRoles. The two measures will be the same: score. But one measure needs to be filtered, and the other should remain unfiltered. The filter, at the moment, would be an on-page slicer.

Is there a way of suppressing the native filtering for one measure?

Or should I create one measure and one category, and the sample data shows automatically when the user filters? If so, how is best to store the population data? 

Thanks for any help. New to custom visuals!

Emma