L4 - Mann-Whitney U

Question 1

When do you use Mann-Whitney U?

Answer 1

Comparing 2 independent samples
Samples don’t need to be equal in size
Use when data isn’t normally distributed or assumptions for parametric tests aren’t met

Question 2

What assumptions are needed in order to carry out Man-Whitney U?

Answer 2

Independent observations
DV should be continuous
Few tied scores in continuous DV

Question 3

How do you calculate Mann-Whitney U?

Answer 3

1. Hypotheses: H0 (no difference) vs.
   H1 (difference).
2. Rank all data points.
3. Sum rank scores for each group.
4. Calculate U values.
5. Check for significance.

Question 4

How do you write Mann-Whitney U to APA style?

Answer 4

Clearly state whether the differences were significant
Include test stats and relevant values