The idea, step by step
A question that expects variation
A statistical question concerns a group and anticipates different answers. “How long do Year 7 students in our class take to travel to school?” identifies a group, a measured variable and a context. “How long did Sam take today?” asks for one value rather than a distribution.
Define the observation clearly before collecting data. For journey time, specify one-way travel, a common school day and the units. Without a shared definition, a five-minute car trip and a full return journey could be mixed together.
Collect comparable, respectful data
Use neutral wording and the same instructions for everyone. “Do you agree the excellent new lunch menu is better?” pressures respondents towards one answer. Ask for their view without praise or criticism in the question.
Decide how to record missing answers and unusual values. Missing is not the same as zero. Keep records anonymous when names are unnecessary, and collect only information needed for the question. A fair procedure makes the conclusions more useful even before calculations begin.
A common trap
A missing response can be entered as 0 to make the table complete.
Instead: Record it as missing. Zero is a valid answer and would change the results.
See the thinking
Make a vague question usable
Improve “How much do people read?” for a class investigation.
- Choose a defined group: students in this Year 7 class.
- Choose one count and time period: whole books finished during the last school term.
- Expect variation rather than one identical answer.
Remove a leading description
Improve “Don't you think our wonderful library should open longer?”
- Remove “don't you think” and “wonderful”.
- Ask about the decision using neutral options.
Check your understanding
Is “What shoe sizes do students in this class wear?” a statistical question?
Show answer
Yes.
It identifies a group and a variable whose recorded values are expected to vary.
Your turn
6 questions · 12 marks · Work at your own pace.
Read the questions online
- Explain why “How tall is Ava?” is not a statistical question about a group.2 marks
- Write a statistical question about the number of pets owned by students in one class.2 marks
- Improve “How many hours are you online?” so all students answer about the same period.2 marks
- Rewrite “Would you choose the boring old sports uniform or the great new one?” neutrally.2 marks
- Four students give no answer to a question about pets. Explain why adding four zeroes is wrong.2 marks
- You want to compare how far two groups can throw a beanbag. Name two collection rules that make the measurements comparable.2 marks
Read the worked solutions
Equivalent correct methods earn the corresponding marks. Include units where asked.
- Explain why “How tall is Ava?” is not a statistical question about a group.2 marks
There is no group distribution to investigate.
It asks for one person's height. - Write a statistical question about the number of pets owned by students in one class.2 marks
A defined class is the group.
Number of pets is the variable and answers can differ.
For example, how many pets does each student in this Year 7 class have at home? - Improve “How many hours are you online?” so all students answer about the same period.2 marks
Specify a common day, units and what activities count.
For example, how many hours did you spend online yesterday, excluding school lessons? - Rewrite “Would you choose the boring old sports uniform or the great new one?” neutrally.2 marks
Remove wording that favours either answer.
Which uniform do you prefer: the current design or the proposed design? - Four students give no answer to a question about pets. Explain why adding four zeroes is wrong.2 marks
Zeroes would add false observations and could reduce a mean or change a mode.
No answer does not mean no pets. - You want to compare how far two groups can throw a beanbag. Name two collection rules that make the measurements comparable.2 marks
Keep conditions and definitions consistent.
Use the same units and a consistent number of attempts.
For example, use the same beanbag and measure from the same throwing line to the first landing point.
Curriculum reference & lesson scope
Australian Curriculum v9 / South Australian Mathematics Curriculum
Year 7 statistical variables, representations, summary statistics, outliers and an original small investigation; deeper sampling methods develop in Year 8.
Official curriculum source ↗