Am I right in saying that 'categorical variables' is the same thing as 'ordinal' ? I notice SPSS statistical software breaks things up into: Ordinal, Scale and Nominal.
Could someone confirm.
"Categorical" seems to have different meanings depending on who you read.
Sometimes it seems to be synonymous with "qualitative" (rather than "quantitative"). Other times it seems to be a more general "discrete" (rather than continuous).
Using the first definition, it would mean "nominal", which means that the data fits into discrete categories with no natural order. Eg. "red", "green", ...
Using the more general definition, it could mean any of "ordinal", "scale" and "ordinal".
"Ordinal" is discrete data like "nominal", but which has a natural order, but no natural scale. For example, "rate this on a scale of 1 to 10". 10 is better than 9, but who is to say that the gap between 10 and 9 is the same as the gap between 6 and 5.
I think "scale" might refer to both continuous and discrete data, but not sure about that. It definitely does refer to discrete data. It is like ordinal data, except there is an obvious scale. An example is taking continuous data such as people's weight, and putting them into 'bins' - 20-30 kg, 30-40 kg, etc.
My (lack of) memory of uni statistics doesn't allow me to answer your second question.
