Data

a collection of facts, such as values or measurements

Data

QUANTITATIVECan be collected using numbers QUALITATIVE

about preferences

Discrete data can only take certain values

Continuous data can take any value

Primary dataYou collect yourself

Secondary data:Someone else has collected

You collect data by doing a Survey

you collect data for every member of the group (the whole "population").

you collect data just for selected members of the group.

A census is accurate, but hard to do. A sample is not as accurate, but may be good enough, and is a lot easier.

SAMPLE CENSUS

Be careful! Don’t bias your survey.

If you measure something several times and all values are close, they may all be wrong if there is a "Bias“

Bias is a systematic (built-in) error which makes all measurements wrong by a certain amount.

Here are five steps to a successful survey:Step one: create the questionsStep two: ask the questionsStep three: display the dataStep four: analyse the dataStep five: present the results

Analyse :study in detail

Display the data

Show the pattern and shape of the data

Give a clear understanding of the data more quickly

Explain and analyse your results

Display: organise the data collected into tables and graphs so that the patterns can be seen and analysed

HOW TO SHOWS DATA Bar Graph Pie Chart

Pictograms Histograms

Bar Charts

• A Bar Chart (also called Bar Graph) is a graphical display of data using bars of different heights.

• For a bar chart you need:• An easy scale for the axes, which you should

label on the axes• A title describing why you have drawn the bar

chart

Pie Chart

• A special chart that uses "pie slices" to show relative sizes of data.

• It is the best way to show fractions or percentages for a set of data

How to Make a Pie Chart Yourself• First add up all your values to get a total• Next, divide each value by the total • Now you need to figure out how many

degrees for each "pie slice" • A Full Circle has 360 degrees, so we do this

calculation: value/total x 360• (You can also multiply (value/total) by 100 to

get a percent

Now you are ready to start drawing!

Draw a circle.Then use your protractor to measure the

degrees of each sector.

Why do you think it is called a pie chart?

Pictograms

• A Pictogram is a way of showing data using images or symbols.

• Each image stands for a certain number of things.• You need:• Simple symbols that are easy to draw• A key showing what each symbol stands for• A title describing why you have draw the

pictograms

Histograms

• A Histogram is a graphical display of data using bars of different heights.

• It is similar to a Bar Chart, but a histogram groups numbers into ranges

• And you decide what ranges to use!

A histogram is different from a bar chart as the bars are joined toghether and have no gaps

A histograms is used for continuous data and for grouped continuous data

Line graph

• Line Graph - A graph that shows information that is connected in some way (such as change over time)