Data display
Displaying and interpreting data
There are lots of ways to show data. When you use charts and diagrams, the information and patterns are easier to see, so you can explain what the data tells you.
Ways to display data
You can show data in many ways: ā¢ Pictograms use symbols with a key. ā¢ Bar charts use bars of different heights. ā¢ Dot plots use one dot for each item. ā¢ Tally charts and frequency tables count how often each value happens. ā¢ Venn and Carroll diagrams sort data into groups. Each one helps you compare or sort data in a different way.
Reading a pictogram
A pictogram uses a symbol to stand for an amount. The key tells you how many each symbol is worth. If the key is 1 symbol = 2 people and chocolate has 4 symbols, then 4 Ć 2 = 8 people chose chocolate. Half a symbol stands for half of the key amount.
Reading a bar chart
A bar chart shows amounts as bars. To read a bar, look across from the top of the bar to the scale. A clear bar chart has a title and labels on both axes, and the bars are drawn neatly with a ruler. Bar charts make it easy to compare amounts at a glance.
Tally charts and frequency tables
A tally chart records data as marks. Each group of five is drawn as four lines with one across them (HH). The frequency column shows the total count for each row. So HH HH II means 5 + 5 + 2 = 12.
Worked examples
Reading a pictogram
- The key is 1 symbol = 4 vehicles. Cars have 5 symbols.
- Multiply the number of symbols by the key: 5 Ć 4.
Answer: 20 cars.
Comparing bars
- Singer 3 got 13 votes from children and 10 from adults.
- 'How many more' means subtract: 13 - 10.
Answer: 3 more children.
Reading a tally chart total
- A tally chart shows frequencies of 5, 17 and 8.
- Add every frequency: 5 + 17 + 8.
Answer: 30 in total.
Where you see this in real life
- Showing a survey of favourite ice cream flavours in a pictogram.
- Counting the vehicles that pass a school in a bar chart.
- Recording votes for a favourite singer in a frequency table.
Key words
- Pictogram
- A chart that uses symbols to show amounts, with a key to say what each is worth.
- Bar chart
- A chart that shows amounts as bars of different heights.
- Key
- A note that tells you how many each symbol in a pictogram stands for.
- Tally chart
- A chart that records data as marks, with each group of five drawn as HH.
- Frequency
- How many times a value or group happens.
- Dot plot
- A chart that shows data with one dot for each item.