Where can I start?

I was asked today a relatively easy question about context filters but I couldn't get myself to answer it.

Why do we need to add the filter into context after putting a "Top N " conditional filter?

This question is relatively easy, I know. We all know that this is because of the order of operation and that's how it is supposed to go but do we know the reason behind this?

To be more specific, the context filter needs to be applied every time we put the conditional filters for data accuracy.

EXAMPLE:

In the figures below we have the count of museums per village/town. Using the conditional filter (Bottom N- villages with the lowest number of museums) we can see in the first graph that Aberdare and Aberdeershire are in the first two places for the lowest number of museums.  If we do the same calculation using the Bottom N filter for the Village/Town, we get a different result( see the second graph). Right now Aberaeron and Aberdare are in the first two places. The reason behind these different results is the Order of Operation.  Tableau manipulated the data.

Also, in both charts we answer different questions. In other words, in the first example we used dimension filters. In the second example we use context filters. As we have already seen, context filters are performed before the dimension filter. This is why we end up with different results.

Hope that would help with some clarifications! It surely helped me understand better.