8.6 Examiner History Report

Z-score

How many standard deviations the examiner is from the mean 

http://www.statisticshowto.com/probability-and-statistics/z-score/

Mean score

Average score given by all examiners for one station

Standard deviation

scored.standard_deviation() --> numpy.std()

https://docs.scipy.org/doc/numpy/reference/generated/numpy.std.html