The metric passivity measures the active contributions of a user compared to his passive content consumption. Hacker et al. (2015) and Viol et al. (2016) calculated this metric based on the text content \ie whether the text contained the word "thanks".

Since there are anonymised datasets without any text content, I propose to use the number of likes compared to the number of replies. Another variant of this metric can be calculated by looking at the ratio of thread views compared to the number of replies created. Because it is calculated for individual users, the metric is of ego-centric scope.

The passivity $p$ is calculated by the ratio of likes versus replies created for a given user:

1. p := select count of likes / count of replies

A passive user is driven by gaining himself benefits and described as a consumer by Angeletou et al. (2011). Viol et al. (2016) describe it as a knowledge seeker, who tries to gain insights, but does not interact with other users. This characteristic is also shared with users who have a low activity overall in the network (c.f. user activity over time). This particular kind of users is active for a temporary time period until they achieve their information needs. Hansen et al. (2010) calls them questioners and Viegas et al. (2004) calls them question askers and newcomers.

A user's lack of communication means that the user does not form social relationships and therefore does not contribute to the Social Capital of the network. Specifically, a like is not sufficient to form a reciprocal interaction. Organisations should be looking to motivate their people to be active in the network as active interactions are a major reason for establishing Social Capital. This is related to the metric user activity over time.