**Statistical Data / Variables – Introduction**

*(Classification of Statistical Data / Variable – Numeric vs Categorical)*

**What is ‘data’ or ‘variable’?**

**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**

**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**.