Collect & organise data
Theory
Data can be collected by asking a survey question or by observing and recording. The results are organised in a tally and frequency table. This Year 5 maths page shows how to write a good question, choose who to ask, keep a tally and read the table.
Categorical data are words or groups (favourite snack, eye colour). Numerical data are numbers you count or measure (number of pets, height in cm).
A good survey question is clear, gives every possible answer once, and does not push people towards one answer.
Some data are better observed than asked for, such as the colours of cars passing the school or the birds in a garden.
A fair sample includes people from every group you want to know about, not just your friends or one class.
Tally marks are drawn in groups of five: four upright strokes and a fifth across them. The frequency is the total count for each category.
Reading a tally and frequency table:
Collecting and organising data
- Write a clear question with a full set of choices.
- Choose who to ask (or what to observe) so the sample is fair.
- Tally each answer as it comes in.
- Count each tally to get the frequency, and check the total.
| \(5 + 5 + 3\) | \(=\) | \(13\) |
\(13\) students.
(i) How many students were surveyed?
(ii) How many more chose popcorn than crackers?
| \(9 + 13 + 6 + 4\) | \(=\) | \(32\) |
| \(13 - 4\) | \(=\) | \(9\) |
(i) \(32\)
(ii) \(9\)
| \(30 - (11 + 6 + 5)\) | \(=\) | \(8\) |
\(8\) white umbrellas.
(i) Each student’s favourite season
(ii) The number of letters in each student’s name
(i) Categorical
(ii) Numerical
"Which kind of book do you like best: adventure, funny, animal, fact or mystery?" It names the choices and asks about the thing he wants to know.
Students from every year, chosen fairly (for example, some from each class), not just one class or one team.
(i) The types of birds visiting the school garden
(ii) Students’ favourite lunch
(i) Observation
(ii) Survey
| \(5 + 5 + 2\) | \(=\) | \(12\) |
She counted only one of the two bundles of five. The frequency is \(12\).
Common pitfalls
Frequently asked questions
What is a frequency?
How many times a category or value occurs.
Why are tallies drawn in fives?
Groups of five are quick to count.
What is the difference between categorical and numerical data?
Categorical data are groups or words; numerical data are counts or measurements.
What makes a good survey question?
It is clear, lists every choice once, and does not lead people to an answer.
How do you find a missing frequency?
Subtract the other frequencies from the total: \(30 - 22 = 8\).