[VagabundoP]

I'd assume this was measure previously, maybe im wrong, but it seems like something you could and would have been measured in the past.

[JadeNB]

But how can you measure except subjectively, and how can you compare subjective measurements when the whole point is that people's very idea of the meaning of phrases like "close friendship" have changed?

[VagabundoP]

Its not my area, but apart from the the person subjective opinion there would be indirect ways to measure it. again I'm just guessing without looking around.