Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
This study empirically examines whether Wikipedia has a neutral point of view. It develops a method for measuring the slant of 28 thousand articles about US politics. In its earliest years, Wikipedia's political entries lean Democrat on average. The slant diminishes during Wikipedia's decade of experience. This change does not arise primarily from revision of existing articles. Most articles arrive with a slant, and most articles change only mildly from their initial slant. The overall slant changes due to the entry of articles with opposite slants, leading toward neutrality for many topics, not necessarily within specific articles.