What is the difference between interval data analysis and ratio data analysis?
Data comes in various sizes and shapes. Two of them are Interval and Ratio. Interval is a measurement where the difference between two values is meaningful and follows a linear scale. For example: in physics, temperature 0.0 on either F or C does not mean 'no temperature'; in biology, a pH of 0.0 does not mean 'no acidity'. Interval data is continuous data where differences are interpretable, ordered, and constant scale, but there is no 'natural' zero. Ratio is the relation in degree or number between two similar things or a relationship between two quantities, ordered, constant scale, with natural zero. Ratio data is interpretable. Ratio data has a natural zero. A good example is birth weight in kg. The distinctions between interval and ratio data are slight. Certain specialized statistics, such as a geometric mean and a coefficient of variation can only be applied to ratio data.