Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
People who belong to the same group often behave alike. Is this because people with similar preferences naturally associate with each other or because group dynamics cause individual preferences and/or the information that they have to converge? We address this question with a natural experiment. We find no evidence that peer political identification affects individual identification. But we do find that peer engagement affects political identification: a more politically engaged peer group encourages individual political affiliation to move from the extremes to the centre.