How to do the test:

  1. State your Null Hypothesis glossary item: 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) glossary item: Critical Significance Level
    This is typically α = 0.05
  3. Calculate the 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 Hypothesisglossary item: Null Hypothesis
    Either compare the calculated statistic with Critical Value,glossary item: 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 result
    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
    Look at the calculated probability (P value) glossary item: probability
    (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
    (Kruskall-Wallis: H = …, df = …, P = …)
    (Kruskall-Wallis: Χ2 = …, df = …, P = …)
    View an example report