MEASURE OF CENTRAL TENDENCY

LEARNING OBJECTIVES

- To be able to find the mean, median and mode from a set of data

- To be able to find the range of a set of data

- To be able to find the mean from continuous grouped data

- To be able to interpret and compare data sets

KEY WORDS

- Mean

- Median

- Mode

- Range

- Frequency distribution

AVERAGES

Averages are used to summarise what the data shows. 

There are 3 types of average: mean, median, mode

The range of distribution can also be found

Lets start with Mode

The mode is the most common value or a repeatative value in a set of data

Example, 

Find the mode of red, blue, green, red, black, red, yellow, green 

Mode = Red, Green

It is also possible to have no mode at all

Example: 1, 2, 3, 4, 5, 6, 7.....

Median

The median is the middle value in a set of data

The first step is to put the numbers in numerical order

Example:

Find the median of 4, 6, 7, 2, 9, 1, 3, 5, 8

Ordered : 1, 2, 3, 4, 5, 6, 7, 8, 9

Median = 5

If there are 2 numbers in the middle. The median is in the middle of these because there can only be one median. 

Example:

Find the median of 7, 2, 6, 4, 8, 3

Ordered: 2, 3, 4, 6, 7, 8

Median = 5

Mean 

To find the mean of a set of data

Add all the values together

Divide by the number of values there are in a set

The mean takes the total of all the values and spreads the total out evenly to get an average

Range

The range of a set of data is the difference between the largest and smallest value

Formula :

Range = largest value - smallest value

Analysing large sets of data?

You use a frequency table! It looks like this

Use a tally to create a frequency table from the used to find the mean in a more