Graphs

What is a bar chart?

• Used when the data is in categories, which are placed on the x-axis

• The mean or frequency is on the y-axis

• Column do not touch and have equal width and spacing

What are pie charts?

Pie charts are used to compare parts of a whole and usually represent data as parts of a circle

How is a pie chart drawn?

• To work out the percentage of each part:

  • Percentage divided by total x100

  • To work out angle of pie segment in degrees, percentage x 3.6

What is a scattergram/scatter diagram?

• Used for measuring the relationship between two variables

• Data form one variable is presented on on the x-axis while the other is presented on the y-axis

• An x is plotted on the graph where the two variables meet

• The pattern of the points may reveal a correlation

What is a histogram?

• Used to represent data on a continuous scale

• Columns touch because each one forms a single score or a related scale like time spent in hours of homework students do each week

• The height shows the frequency

What is a line graph?

• A graph where subsequent plotted points are connected by lines

• Can be used as an alternative to the histogram as the lines show where mid point of each column of the histogram would reach

• Useful for comparing two or more conditions simultaneously