# The Evolution of Wikipedia's Norm Network
## 2 Methods  
To gather data on the network of norms on Wikipedia, we spider links within the \"namespace\" reserved for (among other things) policies, guidelines, processes, and discussion. These pages can be identified because they carry the special prefix \"Wikipedia:\" or \"WP:\". Network nodes are pages. Directed edges between pages occur when one page links to another via at least one hyperlink that meets our filtering criteria; these links are found by parsing the raw HTML of each page and excluding standard navigational templates and lists. Our network is thus both directed and unweighted. We begin our spidering at the (arbitrarily selected) norm page \"Assume good faith\". Details of the spidering process, hyperlink filters and our post-processing of links between pages appear in Appendix A; both the raw data and our processed network are freely available online [42].  
Editors classify pages in the namespace by adding tags; these tags include, most notably, \"policy\", \"guideline\", and \"essay\", among others. When we download page text, we also record these categorizations. These categorizations describe gradated levels of expectations for adherence [43]. In automatically-included \"template\" text, policies are described as \"widely accepted standards\" that \"all editors should normally follow\" [44], guidelines as \"generally accepted standards\" that \"editors should attempt to follow\" and for which \"occasional exceptions may apply\" [45], while essays provide \"advice or opinions\": \"[s]ome essays represent widespread norms,\" while \"others only represent minority viewpoints\" [46]. A fourth category is the \"proposal\", which describes potential policies and guidelines \"still... in development, under discussion, or in the process of gathering consensus for adoption\" [47].  
Previous analysis of Wikipedia's policy environment has emphasized the many, often overlapping, functions that norms play in the encyclopedia, such as policies that both attempt to control un-permitted use of copyrighted material and to establish legitimacy through the use of legal diction and grammar [25]. In the current study, we consider a complementary classification system that focuses on the types of interactions the norms govern, rather than their functions. We propose three distinct norm categories based on, and extending, pre-existing classification of the norms that govern natural [19] and knowledge commons [20].  
Norms may attempt to regulate content creation (\"user-content\" norms) and interactions between users (\"user-user\" norms). In addition, norms may attempt to define a more formal administrative structure with distinct roles, duties, and expectations for admins (\"user-admin\" norms). The two authors of this paper independently categorized a random sample of forty pages using this scheme, and we calculated inter-coder reliability using [PERSON]'s kappa [48].  
For our semantic analysis, we include all text, except that found in special boxes whose text is replicated by template across multiple pages. To build our distribution over one-grams, we normalize all text to lowercase, merge hyphenated words (\"error-correction\" to \"errorcorrection\"), and drop punctuation (\"don't\" to \"dont\"). We do neither stemming nor spelling correction.  
A critical external variable is the number of active users on the encyclopedia at any point in time. Following [49], we define an active user as one who has made five or more edits within a month; these statistics are publicly maintained at [50].