Bitesize has changed! We're updating subjects as fast as we can. Visit our new site to find Bitesize guides and clips - and tell us what you think!
Print

Maths

Tallying, collecting and grouping data

Collecting data

The easiest way to collect data is to use a tally chart.

When collecting data for the number of pets survey, it would have been useful to draw a table similar to this one.

As each person answers the question, we put a tally next to the appropriate number of pets. The frequency column is completed once all of the data has been collected. The table below shows the results of a new pets survey.

Number of pets survey

Number of petsTallyFrequency
0III3
1VIII8
2VVII12
3I1
4II2

These frequencies can be displayed in a bar chart, as shown.

Bar chart showing the frequency against the number of pets owned

Frequency means the 'number of times it occurs'.

In this example, three people had no pets, so the frequency of 0 pets was three.

Remember that the total frequency should be the same as the number of people in your survey. Always check that this is correct.

In this example, we know that 26 people were questioned in the survey. Check this by adding up the frequency totals: 3 + 8 + 12 + 1 + 2 = 26

Here is the same information but this time we have two tables, one for the number of pets owned by boys and one for the number of pets owned by girls.

Number of pets owned by boys

Number of petsTallyFrequency
0II2
1III3
2V5
3I1
4I1

Number of pets owned by girls

Number of petsTallyFrequency
0I1
1V5
2VII7
30
4I1

These frequencies can be displayed in a dual bar chart.

Bar chart showing the frequency of boys and girls against the number of pets owned

We can find more information from looking at this graph.

Question

How many pets were owned by the same number of boys as for girls?

Answer

Four pets.

We can see that the height of the bar is the same for both boys and girls for four pets.

Question

How many more girls than boys were there in the survey?

Answer

Two more girls.

Adding the bars for girls and for boys we find:

  • the total for girls is: 1 + 5 + 7 + 0 + 1 = 14
  • the total boys is: 2 + 3 + 5 + 1 + 1= 12

Activity

Click here to play the activity

Back to Statistics and probability index

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.