Create charts from spreadsheet data, choose a suitable chart type, and label the chart with a title, axis labels and a legend

What this dot point is asking

This outcome is about turning numbers into a chart so they are easier to understand at a glance. You should be able to select the data and create a chart, choose a suitable chart type for the data (column, line or pie), and label the chart properly with a title, axis labels and a legend or data labels. You should also know that a chart linked to the data updates when the data changes. In the written paper you choose and justify a chart type and list its labels; in the practical you build the chart.

The answer

Why use a chart

A chart shows patterns that are hard to spot in a table of numbers, such as which value is largest, how something changes over time, or how a total splits into parts. The right chart makes the message obvious; the wrong chart can confuse.

Choosing the chart type

• Column or bar chart. Best for comparing separate items, such as votes for five lunch options or sales for each month. The taller the bar, the larger the value, so comparisons are easy.
• Line chart. Best for showing change over time, such as temperature across a week or a score across several tests. The line shows the trend rising or falling.
• Pie chart. Best for showing parts of a whole, such as how a budget divides between food, transport and savings. Each slice is a share of the total, so the slices add up to one hundred per cent.

Match the chart to the question: comparing items suggests columns, change over time suggests a line, and shares of a total suggest a pie.

Selecting the data

A chart is built from selected cells. You usually select the labels and the values together, for example the option names and their vote counts. The labels become the categories and the values become the bars, line or slices. Including the headings helps the chart name things correctly.

Labelling the chart

A chart must be labelled or the reader cannot tell what it shows:

• Chart title says what the whole chart is about.
• Axis labels name what each axis shows, such as the categories along the bottom and the quantity up the side.
• Legend or data labels identify each series, bar or slice, especially when there is more than one set of data or a pie has several slices.

Charts update with the data

When a chart is made from a range of cells, it stays linked to them. Change a value and the chart redraws automatically, so you do not rebuild it each time the data changes.

Examples in context

Example 1. Monthly sales. A shop charts twelve months of sales as a column chart so each month's bar can be compared, with a clear title, "Monthly sales", the months along the bottom and the amount up the side. The tallest bar instantly shows the best month.

Example 2. A weekly temperature trend. A geography student plots daily temperature as a line chart, because the line shows the warming and cooling trend across the week far better than separate bars, with the days along the bottom and degrees up the side.

Try this

• Cue. Recommend a chart type to compare the populations of five towns, and give a reason. (A column or bar chart, because it compares separate items side by side so the largest and smallest are easy to see.)

• Cue. List three labels every chart should have. (A chart title, axis labels naming each axis, and a legend or data labels to identify each bar, line or slice.)

• Cue. Explain why a pie chart suits a budget split between food, transport and savings. (A pie chart shows parts of a whole, so each category is a slice and the slices add up to the whole budget.)