Parameter Versus Statistics

Parameters are often estimated

Parameters are normally represented by Greek letters,

The most common parameters are the population mean and variance

Parameter is the fixed, unknown number that describes the population

Statistics

A statistic is a quantitative value that is calculated from the observations in a sample. A statistic is a characteristic of a sample.

They are usually represented by lowercase English letters

The sample mean and variance, two of the most common statistics derived from samples

Known value calculated from a sample

Statistic is often used to estimate a parameter

Observations

In statistics it is often seen that the number assigned to a random variable is called as observations of that variable.