Data Visualisation and Analysis

Charts make data easy to read. Choose a bar, line or pie chart to suit the data, and sum it up with mean, median, mode and range.

Key ideas

• A bar graph compares separate groups, like books read by each class.
• A line graph shows how one value changes over time; the steepest rise is the biggest increase.
• A pie chart shows parts of one whole; all the slices add up to 360°.
• The mean shares the total equally; the median is the middle value once the data is in order.
• The mode is the most common value; the range measures how spread out the data is.
• Reading changes month to month (+ or −) shows trends better than the values alone.

Remember

Watch out

• Finding the median without putting the data in order first.
• Using a pie chart for change over time: use a line graph.
• Picking the month with the highest value instead of the biggest rise from the month before.

Worked example