## Friday, June 18, 2010

### Measure of Central Tendency

- is a value that represents the centre of a set of data
- can be mean, median, mode

Median - the middle number in a set of data after the data has been arranged or ordered

eg. 2, 5, 6, 8, 9 median is 6

eg. 1, 3, 6, 8, 9, 10 median is 7

*add the two middle values together then divide by two : 6 + 8 = 14 14 divided by 2 = 7

*to find the median of data sets with an even number of values (eg. 2, 3, 4, 5, 6, 7) you have to use the above steps (add together , divide sum by 2, or in other words, find the mean/average)

Mode - the most frequently occuring number in a set of data

eg. 3, 5, 7, 7, 9 mode: 7

eg. 2, 2, 4, 6, 6, 8, 11 mode: 2 and 6

eg. 1, 2, 3, 4 mode: none

eg. 1, 2, 2, 2, 3, 3, 4, 4 mode: 2

eg. 2, 3, 2, 3, 4, 2, 4, 3, 4
2, 2, 2, 3, 3, 3, 4, 4, 4 mode: none

Mean - a measure of central tendency
- the sum (adding) of a set of values divided by the number of values in a set

eg. 4, 5, 8, 9, 9
= 4 + 5 + 8 + 9 + 9 divided by 5 = 35 divided by 5
= 7 - this is the mean

Mean - A. K. A. - average

Try these, find Mean, Median, Mode.

A) 7, 8, 6, 9, 9, 5, 7, 7, 8 ,4

4, 5, 6, 7, 7, 7, 8, 8, 9, 9 median: 7 mode: 7 mean: 7

B) 300, 250, 400, 300, 250

250, 250, 300, 300, 400 median: 300 mode: 250 and 300 mean: 300

Here are some websites to give you some extra help if you're still stuck.

http://simon.cs.vt.edu/sosci/Site/MMM/mmm.html

Here is a link to a video that is catchy and helps to remember the mean, median, and mode.