Math Geek picture                     Math Geek                     Math Geek picture

 



Menu


Home

About

Topics


Send text messages to anyone, anywhere, at any time from your computer - anonymously.  Click here.


Sometimes a mean (or average) is not a good estimator of the center of data. The mean is highly influenced by very large or very small values in relation to the rest of the data. For example, if there are 50 data items all fairly close to 32 and a 51st data item of 4 million is put in with the data, that last data item will inflate the mean tremendously. Although this is an extreme case, it shows how the mean is sensitive to extreme values. Sometimes we want a measure for the center of data that is not influenced by extreme values. One such measurement is the median.

To find the median we must first sort the data from smallest to largest. Once that is done, if there are an odd number of data items, the median is the middle data item in the sorted list. If there are an even number of data items, the median is the average of the two middle data items. Here is an example.



Suppose we are given the following data for which to find the median.

21, 23, 11, 11, 4, 29

1. Sort the data set from smallest to largest.

4, 11, 11, 21, 23, 29

2. Since there are an even number of data items, the average of the two middle data items is the median.

The median is the average of 11 and 21 which is 16

See another example

Start quiz

User ID

Password


Registered?
Custom Search

 

© 2012 AFSSC Inc.