# Conflict and Computation on Wikipedia:
## 2 Methods
### Tracking Conflict through Page Reverts  
When editors interact on Wikipedia, they can disagree on what to do and how to behave. The resulting conflicts that emerge can be tracked by reference to \"reverts\". Reverts are when one user takes a page to a previously-seen state, effectively undoing and discarding the work of others. For each page in our sample, the edit time series was coarse-grained into \"revert\" (R) and non-revert (C) actions, as described in Ref. [1]. We define a revert as an edit that takes the page to a previously-seen state (as detected by the MD5 page hash provided by the Wikipedia API), but exclude the relatively small number of cases where a user's revert only undoes work contributed by that user herself (i.e., we exclude self-reverts). More details on these methods, and additional robustness checks, are described in [16].  
Reverts are noisy, imperfect signals of conflict; research has shown how more qualitative, interpretive, \"thicker\" [19] measures of conflict among users are strongly associated with these easily-tracked reverts [20], which can degenerate into edit wars [13]. Researchers have shown that reverts play a central role in marking both conflict and controversy [21; 22; 23], and that a great deal of information is encoded in reverts, including patterns of alliances among editors [10]. Reverts play a major role in the social norms of Wikipedia itself [24], including highly central pages in the norm network such as the \"three-revert rule\", and strong norms against edit warring (see [16] for further discussion).  
Reverts, however, are not equivalent to conflict. In general, reverts are best used to track the presence of task conflict [15], as opposed to other dimensions of conflict identified in the organizational behavior literature, such as affective conflict and process conflict [25; 26]. While the task conflict represented by reverts is more ambiguous than other forms of conflict, it is still highly correlated with affective and relational conflict [27]; for example, the perception of rejection associated with being reverted is a significant factor in dissuading female contributors from participation [28]. At the same time, the tension between the need to change and to retain text can manifest itself in many different and more subtle ways [11; 29; 30]. There are multiple pathways for conflict to manifest itself that do not lead deterministically to reverts, an example being conflict associated with Wikipedia policies [12] and conflict that takes place in discussion on article talk pages [31].  
In short: while we rely on reverts in our analysis here, we emphasize that this is only one signal of conflict on Wikipedia and that conflict itself is a far richer notion than the binary presence-absence data of our time series. The fact that reverts are only noisy, partial signals of conflict leads us to use a particular tool, the hidden Markov model. Hidden Markov models are ideally suited to cases where a complex system leaves only a low-dimensional trace in an observable time-stream, allowing us to reconstruct, in part, some of the structure of the hidden, underlying process.