Average

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A calculated "central" value of a set of numbers.

To find the average we must understand the data we are looking at....

Types of data

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In general we have TWO types of data.

Qualitative & Quantitative

Qualitative - words

Quantitative - numbers

Types of data

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In Mathematics we will usually look at Quantitative data (numbers)

There are TWO types of Quantitative data:

Discrete - Data that can only take certain values [often whole numbers]

Continuous - Data that can take any value (within a range) - [measurements]

Recording Data

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Data can be presented in a number of ways. Often when first collecting data a tally chart is used to then create a frequency table.

Frequency

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How often something happens (usually during a period of time).

A Frequency table is a quick alternative to writing out a list of numbers

Frequency - Two way tables

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Two-way tables are a type of frequency table that can represent two different pieces of information

E.g. Gender and Favourite Subject

Averages

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Now we know how our data can be presented, we can find averages.

Averages

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Mean

• Add up all the numbers,

• Divide by how many numbers there are.

Averages

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Median

• Place the numbers in value order

• Find the middle number.

Averages

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Mode

• Most common number in the list

If you have never heard of these before, have a watch of the next video....be warned the song will stay in your head!

Averages

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Advantages and Disadvantages

It is important the understand when and why we use each of the three different averages.....why do we need three?

Copy down the advantages and disadvantages from the next slide...

Mode is the ONLY average that can be used for Qualitative data!