I thought you said that ordinal data can be converted to interval data for the purpose of creating a control chart. How is that done?
An ordinal scale can be transferred to an interval scale by additional analysis. For example, if we have an ordinal severity scale, one can calculate from this scale an interval scale by regressing patients’ survival on the ordinal scale. Then average values for each level in the ordinal scale will have interval scale properties. Thank you for the question. This question was asked on 6/24/2005 10:09:37 PM and answered on 6/28/2005 10:02:06 PM.