Understand the idea.
A question that expects variation
A statistical question expects variation across a group. Specify who is included, what feature is recorded and the relevant period. Asking about a class’s journey times expects several different values; asking one person’s journey time today asks for one value.
Define the variable consistently before collecting responses. For journey time, specify a one-way trip, a common kind of day and a unit such as minutes. Shared definitions stop unlike quantities from being mixed into one dataset.
Collect comparable, respectful data
Use neutral wording so respondents can give their own view. Praise, criticism or phrases such as “don’t you agree” can steer answers. Offer clear options that address the decision and use the same instructions for everyone.
Plan how to record missing or unusual responses. A blank means the value is unknown, not zero. Collect only the information needed, omit names when unnecessary, and explain conclusions within the limits of the group actually investigated.
See the method in action.
Make a vague question usable
Improve “How much do people read?” for a class investigation.
Worked solution
- 1
Define the group being investigated.
Students in this Year 7 class form a clear group, whereas “people” leaves the group unspecified.
- 2
Define a count and a common period.
Whole books finished during the last school term gives everyone the same variable and time frame.
- 3
Write the statistical question.
Ask: “How many whole books did students in this Year 7 class finish during the last school term?” Different students can give different counts.
How many whole books did students in this Year 7 class finish during the last school term?
Remove a leading description
Improve “Don't you think our wonderful library should open longer?”
Worked solution
- 1
Remove the words that steer the answer.
“Don’t you think” and “wonderful” encourage agreement instead of neutrally requesting a preference.
- 2
Identify the decision being investigated.
The relevant preference concerns the library’s closing time.
- 3
Ask with neutral alternatives.
Ask: “Would you prefer the library to close earlier, at its current time, or later?” Each offered direction can be selected without agreeing with praise.
Would you prefer the library to close earlier, at its current time, or later?
Try it yourself.
Check your understanding
Is “What shoe sizes do students in this class wear?” a statistical question?
Show answer & reasoning
Yes.
Yes. The question specifies students in this class and records shoe size. Sizes are expected to vary across that group, so the question anticipates a distribution of responses.
Keep practising
6 worksheet questions · 12 marks
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 ↗