  The friendship paradox is the phenomenon that in social networks, people on
average have fewer friends than their friends do. The generalized friendship
paradox is an extension to attributes other than the number of friends. The
friendship paradox and its generalized version have gathered recent attention
due to the information they provide about network structure and local
inequalities. In this paper, we propose several measures of nodal qualities
which capture different aspects of their activities and influence in online
social networks. Using these measures we analyse the prevalence of the
generalized friendship paradox over Twitter and we report high levels of
prevalence (up to over 90\% of nodes). We contend that this prevalence of the
friendship paradox and its generalized version arise because of the
hierarchical nature of the connections in the network. This hierarchy is nested
as opposed to being star-like. We conclude that these paradoxes are collective
phenomena not created merely by a minority of well-connected or high-attribute
nodes. Moreover, our results show that a large fraction of individuals can
experience the generalized friendship paradox even in the absence of a
significant correlation between degrees and attributes.
