# Best way to handle disappearing search facets?

As part of a faceted search system I'm putting together, I have a series of checkboxes for different neighbourhoods in a city, like so:

[ ] Neighbourhood 1 (50)
[x] Neighbourhood 2 (40)
[ ] Neighbourhood 3 (30)
[ ] Neighbourhood 4 (20)
[ ] Neighbourhood 5 (10)


Now, there can be over 100 in any given city, so showing them all isn't really very practical. The compromise I've come up with (and I'm not very happy with it, as it loses the ability to scan alphabetically) is to have the six most popular neighbourhoods and a link to "See More..."

So far so good. But there are other facets- what should I do when a selected neighbourhood no longer belongs on the ordered list? For example, I change some other facets, now the list above looks like:

[ ] Neighbourhood 4 (16)
[ ] Neighbourhood 1 (13)
[ ] Neighbourhood 3 (11)
[ ] Neighbourhood 5 (10)
[ ] Neighbourhood 6 (8)


...and then, not on this list is my checked neighbourhood:

[x] Neighbourhood 2 (6)


I don't want to remove a checkbox that a user has already chosen, it seems like it will make things very confusing. But what are my options? Has anyone experienced this before? I'm considering either overriding the list order to make sure that checked options are always included in the list, or just making the list X checkboxes longer and including the checked neighbourhoods. Neither seems like a great solution though.

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Why isn't it in the list if there are 6 hits? (The (6) in your example). If it has been checked, just include it with a hit count of 0 to indicate that the other criteria (facets) mean there aren't any in the selected neigborhood. –  Marjan Venema Jan 26 '11 at 7:02