NUMBAT OER - Open Educational Resources

How to do the test:

  1. State your Null Hypothesis in the form: "There is no difference between the populations from which the two 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:

    1. Compare the calculated statistic with Critical Value:
      CASE A - using critical values of the H statistic:
      • If H ≥ Hcritical → reject H0 → significant result.
      • If H < Hcritical → accept H0 → non-significant resul.t
      CASE B - comparing H with critical values of the Χ2 statistic for large amounts of data:
      • If H ≥ Χ2critical → reject H0 → significant result.
      • If H < Χ2critical → accept H0 → non-significant result.
    2. Look at the calculated probability (P value):
      (SPSS calculates the X2 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.
    Either:

    • Kruskall-Wallis: H = …, df = …, P = …
    • Kruskall-Wallis: Χ2 = …, df = …, P = …

    View an example report.