How to teach the statistical investigation process
Year 7 to Year 9 (ages 12 to 15)
A statistical investigation follows a repeatable cycle: pose a question, plan how to collect data, collect it, analyse it, and draw a conclusion that answers the original question. Each stage depends on the one before it.
How to teach it
- Teach the cycle by name (Problem, Plan, Data, Analysis, Conclusion) so students can identify which stage they are in at any time.
- Start with the Problem stage: a good statistical question is answerable with data, not just a yes/no opinion.
- Spend real time on the Plan stage: what data is needed, how much, and how to collect it fairly, before touching a single number.
- In Analysis, connect back to skills already learned (mean, median, mode, displays) to summarise the collected data.
- Insist every Conclusion refers back to the original question and acknowledges any limits (small sample, possible bias).
Common mistakes
- Jumping straight to collecting data without a clear question or a plan for how to collect it.
- Writing a conclusion that does not actually answer the original question posed.
- Treating one sample's result as absolute fact rather than an estimate with natural variation.
- Skipping the Analysis stage's organisation step and jumping straight to a conclusion from raw, unsummarised data.
Frequently asked questions
What are the stages of a statistical investigation?
The PPDAC cycle: Problem (pose the question), Plan (decide what data to collect and how), Data (collect it), Analysis (organise, display and summarise it), and Conclusion (answer the original question based on the evidence).
Why should you plan data collection before starting?
A plan ensures the data actually answers your question and is collected consistently. Without one, you risk gathering data that cannot answer what you originally set out to investigate.
Why can two different samples give different results for the same question?
This is natural sampling variation: different samples do not always give identical results, even when chosen the same way. A good conclusion accounts for this rather than treating one sample as the final truth.
What year is the statistical investigation process taught?
In the Australian Curriculum this spans Year 7 to Year 9: planning and carrying out an investigation with numerical data at Year 7 (AC9M7ST03), investigating a sampled population at Year 8 (AC9M8ST04), and weighing the strength of evidence for a conclusion at Year 9 (AC9M9ST05).
Practise with free worksheets
Printable worksheets with answer keys that are never wrong.