Mann Whitney U

• how to calculate Mann Whitney U?

  1. rank all scores together from lowest to highest
  2. add up all ranks from condition 1
  3. repeat step 2 for condition 2
  4. use the formula to find the smallest total value
  5. use the table of critical values for the test
• formula

  U = R - $\frac{n\ \left(n+1\right)}{2}$
• observed value less than or equal to critical value

  difference between the scores is significant so null hypothesis is rejected and alternative hypothesis is accepted
• observed value is greater than critical value

  difference if not significant so null hypothesis is accepted and alternative hypothesis is rejected