A theory-based intervention to prevent calibration effects in serial sport performance evaluations

ObjectivesSerial performance evaluations show calibration effects: Judges avoid extreme categories in the beginning (e.g. best or worst) because they need to calibrate an internal judgment scale (Unkelbach et al., 2012). Successful calibration is therefore important for fair and unbiased evaluations. A central prerequisite for successful calibration is knowledge about the performance range. The present study tests whether advance knowledge about the range (best and worst) of performances in a series reduces calibration effects.DesignA 2 × 2 × 2 design was developed with two between subject factors: the knowledge about the performance range (with vs. without) and two different talent tests (specific vs. unspecific). As within subject factor the position of the performances in the series (position 1–10 vs. 11–20) was integrated. The combination of the between subject factors resulted in four experimental conditions.MethodHandball coaches were randomly assigned to one of the conditions. Afterwards twenty performances were evaluated in a randomized order by the coaches.ResultsWithout knowledge about the range, they showed the expected avoidance of extreme categories in the beginning independent of the presented talent test. However, observing the best and worst performance in advance prevented the biases. Range-presentation is therefore a viable theory-based intervention to improve fairness in serial judgments.     

The Jack the Ripper murders: a modus operandi and signature analysis of the 1888–1891 Whitechapel murders

A number of females, commonly recognized as 11 victims, were murdered in separate events in Whitechapel, London between 1888 and 1891. An evaluation of the murders revealed that six of those murders were linked by a number of distinct, personal signature characteristics, including picquerism, overkill, incapacitation, domination and control, open and displayed, unusual body position, sexual degradation, mutilation, organ harvesting, specific areas of attack, preplanning and organization, and a combination of signature features. The signature characteristics observed in these infamous Jack the Ripper murders were compared to a 1981–1995 cohort of 3359 homicide cases from Washington State's HITS database. The analysis revealed that the signature displayed in six of the Whitechapel murders was extremely rare. There were only six records of female victims, one a prostitute, with probed, explored, or mutilated body cavities. There were only two cases, both females who were not prostitutes, where the body was left in an unusual position and body cavities were explored, probed, or mutilated. Copyright © 2005 John Wiley & Sons, Ltd.