Q&A from AQA: Levels of Measurement

Below you will find a question and response from AQA in relation to: Levels of Measurement.

Question

Is ‘at least ordinal data’ acceptable? Which type of data is required for the Wilcoxon test?

Response

If the data is at least ordinal then Wilcoxon is still appropriate the criteria for this test does not change even if the sign test is now being added onto the specification. Sometimes there is more than one stats test that is appropriate for the study and the candidate must justify their choice to get the credit. At AS they only need to understand and apply the sign test but at A level they need to know more tests and justify their choice.