hello, I am a student and I am doing a project that consists of calculating Mann Whitney U test. I would like to know the definition of mean rank that is calculated with this analysis. Also, I would like to know what is the difference between median and mean rank?

Support Member

For the formulas being used on Mann Whitney test see the Statistics algorithms manual pdf here:

ftp://public.dhe.ibm.com/software/analytics/spss/documentation/statistics/27.0/en/client/Manuals/IBM_SPSS_Statistics_Algorithms.pdf

See algorithms for nonparametric tests, Mann Whitney test from page 757 and following.

The median is simply the value in the middle of your sorted series of values. For example you have 5 cases with 5 values in a certain variable: 23, 45, 60, 78, 99.

On above list the median is the value 60 because below this value are 50% of cases and above this value are 50% of cases. Mean rank formula can be found on above PDF doc