Can credit card pin numbers be described as Qualitative  Ordinal?
Well, they can be. In fact most PIN numbers start with $1$, because for one thing people tend to use dates in the $1900s$ and also Benford's law shares some of the blame. So treating them as if they have a numeric meaning can actually yield some insights.
The reason they are considered "nominal" is that for most purposes their numeric value has no meaning. To verify a transaction all that matters is that the PIN entered matches the one on file, i.e. we need only to be able to determine if $2$ PINs are the same. There are still investigations that can be made on that basis, for example exactly how common is the $n^{th}$ most common PIN?
Your idea about measuring the complexity is also fine. Perhaps having a weak PIN is correlated with being a fraud victim in which case it could make sense to compute a "complexity score" from the PIN and treat that as a quantitative value.
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roundar
Updated on August 22, 2020Comments

roundar about 3 years
I've just started taking statistics. Today the class was asked what type of data are credit card pins.
The lecture leading up to the question gave us the following: Data can be described as being quantitative or qualitative. If qualitative, it can be described as nominal or ordinal. In order to be ordinal, you must be able to order the data in a meaningful way; therefore, being able to order pins from least to greatest does not make them ordinal, I know.
I am wondering though, why can't pins be described as ordinal given they can be ordered in terms of complexity, by the number of repeating digits, etc? EDIT: In this case, the order would be meaningful in a study about links between simple pin numbers and stolen credit cards for instance.

roundar about 10 yearsThank you. So the pin numbers are definitely nominal and a "complexity score" would be a new piece of ordinal data?

Dan Brumleve about 10 yearsYes, except like I explained in the first paragraph PIN numbers aren't always nominal.