Fixed measurement units with no absolute, or fixed, zero point
Scientific measures used to record the distance between values are highly reliable.
Numbers assigned to objects or events representing the rank order
It is more informative than nominal data;however, gaps between the values aren't equal so a mean cannot be used to assess central tendency.
Numbers representing fixed measuring units and having an absolute zero point
Values come from fixed points in time so they are historicaly grounded and may not represent predictive value.
Variables whose values have no mathematical interpretation
This data is easy to generate from closed questions, large amounts of questions can be collected quickly, and it offers increasing reliability.