Blog Post
Interesting, but surprisingly uni-dimentional: closer relations are those frequently updated because of dedicated investment)? That's a bit sad, is it?
I love the effort, but you might want to enrich that with what Carolyne Haythornwaithe (http://scholar.google.com/scholar?q=Caroline+Haythornthwaite) and Bernie Hogan (http://people.oii.ox.ac.uk/hogan/publications/) did around how closer ties are those who use many tools or pertain to several contexts… What she said about latent ties is enlightening, too : http://scholar.google.com/scholar?cluster=13178497937079720091&hl=fr&as_sdt=2000
Now that, thanks to smartphone, we have data on where people are, spend their time, etc. there is considerable rsearch to separate interactions (implicitly with colleagues) with attachement (including trust in long-lost friends).