The problem:

We were working on National Student Survey data last week, most of us had filters for ‘University Group’, ‘University Name’, and ‘Subject’. The Subject filter has a very long list, the users could get confused if they were to click on one of those courses which isn’t offered by the selected university, since the view would just disappear.

The solution:

Click on the dropdown menu next to the Subject filter, switch the option from ‘All Values in Database’ to ‘Only Relevant Values’.

Now the list becomes much shorter with all values relevant to the selected university.

Thanks Andy for pointing out the potential problem with this function. If I set show ‘Only Relevant Values’ for both Category (Country in this case) and Sub category (Subject), once I filter Country, Subject reduces as shown before, however, if I filter Subject, Country reduces as well.

Now if I want to pick ‘Wales’ from Country, I’ll have to select ‘All’ from Subject.

The show ‘Only Relevant Values’ option only works well when we would want to filter down the categories. In this case,  we have two hierarchical filters, it would be best if we keep the upper level filter (Country) as from ‘All Values in Database’.

There is a very helpful TIL blog post explaining filters in Tableau if you need more than two hierarchical filters.