Median – Statistics and Probability

THE MEDIAN

The median is defined as an average which is the middle value when figures are arranged in order of magnitude.

In an even distribution, he median is the average of the two middle numbers. The median is therefore the value of the middle item.

Example

Find the median of the following sets of values 2, 8 , 11, 13, 15, 6 , 9, 20, 7

Formula, median = N + ½

When n is the number of items (observation). This formula is applicable when n is odd

Solution:

2, 6, 8., 9, 11, 13, 15, 20

Median = 9 or 9+1/2 = 10/2

= 5 (the 5^th member in ascending magnitude is 9)

= 9

ADVANTAGE OF MEDIAN

1. Computation in median is very easy
2. Median is not affected by extreme of values
3. It is very easy to understand
4. It can be obtained by graphic form
5. The median is easy to determine by mere observation
6. Median can be determined from frequency graph
7. Median can be used to find the average student or examination or to find the worker with an average salary

DISADVANTAGES OF MEDIAN

1. Difficulties come when lager values are involved
2. Median cannot be used to calculate the values of all the items
3. Median is likely to be unrepresentative of all the values in the data, if the data are few
4. Arrangement of data in order of magnitude is not easy if large figures are involved
5. Median cannot be used for further mathematics calculation.