Applicable Properties and Permissible Transformations for Four Types of Measurement Scales

PROPERTIES of the numbers that apply:
Nominal
Ordinal
Interval
Ratio
similarities and differences
x
x
x
x
rank order
x
x
x
magnitude of differences
x
x
ratios & meaningful zero point
x
TRANSFORMATIONS of the data that are ok:
Nominal Ordinal Interval Ratio
change labels in any way that keeps the same-vs.-different relationships intact
x
     
make any change that preserves order information
x
x
   
add a constant
x
x
x
 
multiply by a positive constant
x
x
x
x