7.2.1 Description

In the previous project (Project 2.2: Validating cardinal domains — measures, counts, and durations), we looked at attributes that contained cardinal data – measures and counts. We also need to look at ordinal and nominal data. Ordinal data is generally used to provide ranks and ordering. Nominal data is best thought of as codes made up of strings of digits. Values like US postal codes and bank account numbers are nominal data.

When we look at the CO2 PPM — Trends in Atmospheric Carbon Dioxide data set, available at https://datahub.io/core/co2-ppm, it has dates that are provided in two forms: as a year-month-day string and as a decimal number. The decimal number positions the first day of the month within the year as a whole.

It’s instructive to use ordinal day numbers to compute unique values for each date and compare these with the supplied ”Decimal Date” value. An integer day number may be more useful than the decimal date...