Hugh Pickens writes "A new study shows that the patterns of collaboration among Wikipedia contributors directly affect the quality of an article. 'These collaboration patterns either help increase quality or are detrimental to data quality,' says Sudha Ram at the University of Arizona. Wikipedia has an internal quality rating system for entries, with featured articles at the top, followed by A, B, and C-level entries. Ram and graduate student Jun Liu randomly collected 400 articles at each quality level. 'We used data mining techniques and identified various patterns of collaboration based on the provenance or, more specifically, who does what to Wikipedia articles,' says Ram. The researchers identified seven specific roles that Wikipedia contributors play (PDF starting on page 175): Casual Contributor, Starter, Cleaner, Copy Editor, Content Justifier, Watchdog, and All-round Editor. Starters, for example, create sentences but seldom engage in other actions. Content justifiers create sentences and justify them with resources and links. The all-round contributors perform many different functions. 'We then clustered the articles based on these roles and examined the collaboration patterns within each cluster to see what kind of quality resulted,' says Ram. 'We found that all-round contributors dominated the best-quality entries. In the entries with the lowest quality, starters and casual contributors dominated.'"