Data : The numerical representation of facts is called data.
Observation : Each entry in the data is called an observation.
Variable : The quantities which are being considered in a survey are called variables.
Variables are generally denoted by xi , i =1,2,3,…,n.
Frequencies : The number of times, a variable occurs in a given data is called the frequency of that variable. Frequencies are generally denoted as fi , i = 1,2,3,…,n.
Arithmetic Mean
Median
Mode