Qualitative variables
are variables that have distinct categories according to some
characteristic or attribute.
Quantitative variables
are variables that can be counted or measured.
Discrete variables
assume values that can be counted.
Continuous Variables
can assume an infinite number of values between any two specific values. They often include fractions and decimals
nominal level of measurement
classifies data into mutually exclusive (nonover-
lapping) categories in which no order or ranking can be imposed on the data.
ordinal level of measurement
classifies data into categories that can be
ranked; however, precise differences between the ranks do not exist.
interval level of measurement
ranks data, and precise differences between
units of measure do exist; however, there is no meaningful zero.
The ratio level of measurement
possesses all the characteristics of interval
measurement, and there exists a true zero. In addition, true ratios exist when the
same variable is measured on two different members of the population.