Closeness Centrality

Nov 11, 2014 at 3:12 PM

I'm looking for a bit of help with regards to closeness centrality. In the NodeXL book it states that the lowest possible closeness centrality score is equal to 1. Is this per vertex? As I am looking at Facebook networks which show all interactions within a fan page and each closeness centrality score for each vertex only goes up to 0.23. (which is obviously not equal to 1). What does this show?