Interval Measurement: It is a scale based on equal units of measurement indicating how much of a given attribute is present in the subject. It exhibits equal differences ia amounts. Example : Temperature limitation of this scale is : it fails to measure absolute magnitude. The scale does not have a true zero. Continues variable yield interval measurement. Analytical possibilities are greater. The data can be meaningfully added, subtracted and averaged. i.e. If (a = b) and (b = c), then (a - c).
The interval from a to c =3-1 = 2. The interval from c to d =4-3 = 1. We can add this (3-1) + (4-3) = 2+1 = 3. Now note that the interval from a to d = 4-1 = 3. Expressed in an equation (d-a) = (c-a) + (d-c).
The statistics applicable are:
- can explore mathematical relationship, such as Mean, SD (Standard Deviation), product moment correlation, Standard Error, Variance etc.