  ## How to do the test:

1. State your Null Hypothesis in the form:
"There is no difference between the populations from which two unrelated samples come"
2. Choose a Critical Significance Level (α: alpha):
This is typically α = 0.05.
3. Calculate the test statistic:
Use a spreadsheet to calculate your results, or access a helpsheet for SPSS and check here for data entry into SPSS.
4. Reject or accept your Null Hypothesis.
Either
NOTE: The calculation yields two values of the U statistic. Either can be used, but both the spreadsheet and SPSS use the smaller value. Thus:
1. Compare the calculated statistic with critical values (Critical values table):
• If F ≥ Ucritical → reject H0 → significant result.
• If U < Ucritical → accept H0 → non-significant result.
2. Look at the calculated probability (P value):
• If P ≤ α → reject H0 → significant result.
• If P > α → accept H0 → non-significant result.
5. Report your results:
Plot your data using the appropriate graphs.
(Mann-Whitney U test: U = …, n1 = …, n2 = …, P = …)