Statistical Procedure

This procedure can be used when the:

Outcome (Dependent) variable is a Continuous and skewed / Ordinal measure
Exposure (Independent) variable is >2 related samples

Present this graphically using a Box and Whisker Plot

In SPSS select: Graphs > Chart Builder - Gallery – Boxplot | Simple Boxplot or Scatter/Dot | Simple Dot Plot

Analyse this in SPSS using:

Analyze >NonParametric Tests > Legacy Dialogs > K Related Samples
Use the Exact button and select Exact, Statistics button and select Quartiles

The Exact Sig. is the p-value.

Report this quoting the:

p-value and presenting the Medians for each sample

References

Chapter 15, p 573 in Discovering Statistics using SPSS 3rd Edition, A. Field, Sage Publications (2009) (ISBN: 9781847879073)

Please Report any issues to Brian Yuen