The Mean (average)

Mean is the sum of the values, divided by the total number of values.

In the case that we have a finite population with \(n\) subjects, i.e. \(P=\{x_1,...,x_n\}\), and \(x_i\) is quantitative data for subject \(i\) then the mean is calculated by the following formula:

\[\mu=\frac{\Big(\sum_{i=1}^nx_i\Big)}{n}\]

Notice that we use the Greek letter \(\mu\) "mew" for population mean!

In the case that we have a finite sample with \(n\) subjects, i.e. \(S=\{x_1,...,x_n\}\), and \(x_i\) is quantitative data for subject \(i\) then the mean is calculated by the following formula:

\[\overline{x}=\frac{\Big(\sum_{i=1}^nx_i\Big)}{n}\]

Notice that we use the symbol \(\overline{x}\) "\(x\)-bar" for sample mean!