• Data points where there is a sense of order and rank. In addition, the magnitude of difference between each number is the same and measurable.
• Made up of two types of scales of data, interval scale and ratio scale.
• The only difference between interval and ration scale data is whether or not the scale being referred to has an absolute zero. 
• Interval scale data:
• When numbers have units that are of equal magnitude as well as rank order on a scale without an absolute zero
• Scales of this type can have an arbitrarily assigned "zero", but it will not correspond to an absence of the measured variable.  For example, temperature in Fahrenheit scale. 
• Ratio scale data:
• When numbers have units that are of equal magnitude as well as rank order on a scale with an absolute zero
  
• Examples include: heart rate, blood pressure, distance.

• For interval and ratio data can be converted into ordinal data, but ordinal data cannot be converted into continuous data.
• Can be described as a mean or median.

• Parametric Statistical Analysis
• Nonparametric Statistical Analysis
• Nominal Data
• Ordinal Data
  

1. Gaddis ML et al. Introduction to biostatistics: part 1, basic concepts. Ann Emerg Med 1990;19:86-89.

Editors:

• Anthony J. Busti, MD, PharmD, FNLA, FAHA
• Karolina DeAugustinis, MD 

Last Reviewed: July 2015