Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Making use of a subjective performance appraisal system, it is a well-established fact that many supervisors tend to assess the employees too good (leniency bias) and that the appraisals hardly vary across employees of a certain supervisor (centrality bias). We explain these two biases in a simple theoretical model and discuss determinants of the size of the biases.