Figure 4

Mixing patterns for different activities in aNobii. The notation $n_{x,\mathit{nn}}(n_x)$ indicates the average amount of an activity x performed by the nearest neighbors of those users that expose the same amount $n_x$ of that activity. As defined before, $k_{\mathrm{out}}$, $n_b$, $n_w$, $n_g$, $n_t$, $n_a$, $n_r$, $n_s$ denote respectively the out-degree and the number of books, wishlist items, group memberships, tags, tag annotations, reviews and ratings.