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Data & Statistics · Lesson 8 of 14

Collecting Data and Asking Fair Questions

Good data starts with a good question. A fair question is clear, has useful answer choices and is asked to a sample that represents everyone.

What you will learn

  • Plan a survey from a clear question.
  • Write fair questions and useful answer choices.
  • Pick a sample that represents everyone, and record the answers.

Before you start: you should be able to use tally marks. See Counting with Tally Marks.

The idea

Data is information you collect. A survey asks the same question to many people and records the answers. To trust the results, you need three things: a clear question, sensible answer choices and a fair sample, which is the group you ask.

Sorted into groups: Fair question, Unfair questionFair question: Which fruit do you like best?, Pick one: bus, walk, car, bike or other. Unfair question: Isn't fruit great?, Wouldn't you rather walk?.Fair questionWhich fruit do you like best?Pick one: bus, walk, car, bike or otherUnfair questionIsn't fruit great?Wouldn't you rather walk?
Fair questions do not hint at the answer you want. Unfair ones push people towards it.

Planning a survey

  1. Decide what you want to find out.
  2. Write one clear question with answer choices that cover everyone, including “other”.
  3. Decide who to ask and how many.
  4. Collect the answers with a tally chart.
  5. Count, compare and draw a chart.

Choosing a sample

If you only ask your friends, you may get answers that are not like the rest of the school. A better sample includes people from different groups. A bigger sample is usually more reliable than a small one.

Tally chart: Walk 14, Bus 9, Car 6, Bike 4, Other 2Tally chart: Walk 14, Bus 9, Car 6, Bike 4, Other 2. Groups of five are four lines with a strike through.Walk14Bus9Car6Bike4Other2
A tally of how 35 pupils travel to school. Walking is the most common, with 14 out of 35, which is 40%.

Worked examples

Example 1: Fixing a question

Improve: “Don’t you think pizza is the best food?”

  1. The question hints at the answer you want.
  2. Rewrite: “Which of these foods do you like best: pizza, pasta, rice, salad or other?”

Answer: a neutral question with choices that cover everyone

Example 2: Percentage from a tally

3535 pupils were asked. 1414 walk. What percentage walk?

  1. 14÷35=0.414 \div 35 = 0.4.
  2. 0.4×100=40%0.4 \times 100 = 40\%.

Answer: 40%40\%

Example 3: Spotting a biased sample

A pupil asks only the school football team: “Do you like football?” Is the result fair?

  1. The team is not typical of the whole school.
  2. They are likely to say yes.

Answer: no, the sample is biased. Ask pupils from every year and from different activities.

Tip: try your question on two or three people first. If they are confused, rewrite it.

Why it matters

Polls, product reviews and school council votes all depend on how the data was collected. Fair questions and fair samples are what make results believable. Next, learn to organise results in frequency tables and dot plots.

Practice

Your turn. Type or choose an answer, then press Check. Getting one wrong is fine, that is what practice is for. You can try as many times as you like.

Question 1 of 8

Which question is fairest?

Choose one answer

Question 2 of 8

You want to know the favourite sport of a whole school. Who is the best group to ask?

Choose one answer

Question 3 of 8

5050 pupils were asked and 2020 chose football. What percentage chose football?

Question 4 of 8

A survey asked 2525 pupils and 55 chose swimming. What percentage chose swimming?

Question 5 of 8

Why is "How much do you like our wonderful school?" a poor question?

Choose one answer

Question 6 of 8

A tally records 1313 votes for cats and 99 for dogs. How many votes in all?

Question 7 of 8

Which answer choices are best for "How do you travel to school?"

Choose one answer

Question 8 of 8

You ask 88 friends from one class and then 1212 pupils from other classes. How many pupils have you asked altogether?