Statistical Data / Variables – Introduction
(Classification of Statistical Data / Variable – Numeric vs Categorical)
What is ‘data’ or ‘variable’?
Ø Data is a set of values of qualitative or quantitative variables.
Ø In biostatistics (also in statistics) data are the individual observations.
Ø The scientific investigations involve observations on variables.
Ø The observations made on these variables are obtained in the form of ‘data’.
Ø Variable is a quantity or characteristic which can ‘vary from one individual to another’.
Ø Example: Consider the characteristic ‘weight’ of individuals and let it be denoted by the letter ‘N’. The value of ‘N’ varies from one individual to another and thus, ‘N’ is a variable.
Ø Data and variable are not exact but used frequently as synonyms.
Ø The variables can also be called as ‘data items’.
Ø Majority of the statistical analysis are done on variables.
Type of Variables in Statistics
Statistical variables can be classified based on two criterion (I) Nature of Variables and (II) Source of variables
I. Classification of variable based on Nature of Variables
Ø Based on the nature of variables, statistical variables can be classified to TWO major categories such as (1) Numerical and (2) Categorical.