Mann-Whitney U

Question 1

difference of Mann-Whitney U to other significance tests

Answer 1

the only test where the U value has to be less or equal to the critical value to be significant

Question 2

when is a Mann-Whitney U used

Answer 2

to compare two medians

Question 3

how to calculate

Answer 3

• rank two sets of observations, switching between the rows
• add up rows 1 and 4 (ranks)
• na and nb are the amount of observations in data set
• check work but substituting into checking equation
• then substitute into Mann Whitney calculation
• use smaller value to apply to significance table