We have 8 years of data that includes info on all crimes reported to MPs and all crimes the commanders submitted for prosecution. This is not a sample - it is the entire population of crimes committed by members of the Army. We are studying domestic violence and among other things we are looking at the relationship between offender rank and the actions taken by the commanders (who function as prosecutors). The data is primarily nominal and ordinal data and normally we would run significance tests but those are designed for samples. Are p-values even meaningful when you have the entire population and do not need to wonder if the sample is representative of the population? Any suggestions for methods of analysis?