nominal (categorical)-male, female; republican, democrat, etc:

ordinal- ranked values such as 1st place, 2nd place, etc; economic status:

no exciting test to do

interval- difference between the values is meaningful $600 vs $700: (not meaningful) how happy you are on a scale of 1-10:

Standard Deviation, regression, correlation, ANOVA

Ratio- defined 0 GPA,Kelvin:

All tests