Arithmetic mean or mean
Central value is called a measure of central tendency or an average or a measure of locations. There are five averages. Among them mean, median and mode are called simple averages and the other two averages geometric mean and harmonic mean are called special averages.
· “A measure of central tendency is a typical value around which other figures congregate.”
· “An average stands for the whole group of which it forms a part yet represents the whole.”
· “One of the most widely used set of summary figures is known as measures of location.”
The mean of a variable is defined as the sum of the observations divided by the number of observations. If the variable x assumes n values x1, x2 … xn then the mean, , is given by summing of all x values divided by the number of x values.
This formula is for ungrouped or raw data.