Before data can be analysed or displayed, it must be collected. The method chosen affects the quality and reliability of the results. Foundation Mathematics focuses on three core collection methods: surveys, observation, and measurement.
KEY TAKEAWAY: The right collection method depends on what you want to find out and whether you can interact with the subject.
A survey collects information by asking people questions.
Poor questions lead to unreliable data. Good survey questions are:
- Clear: Unambiguous wording
- Unbiased: Don’t lead the respondent toward a particular answer
- Closed or open: Closed questions have set options (easier to analyse); open questions allow any response
| Poor Question | Problem | Better Question |
|---|---|---|
| “Don’t you agree the canteen food is bad?” | Leading | “How would you rate the canteen food?” |
| “How much do you exercise?” | Vague | “How many hours per week do you exercise? (0–1, 1–3, 3–5, 5+)” |
Rarely can you survey everyone (the whole population). Instead you survey a sample.
- Random sample: Everyone has an equal chance of being selected — most reliable
- Convenience sample: Easiest to collect (e.g. asking classmates) — may be biased
EXAM TIP: When asked to evaluate a survey, consider: Was the sample large enough? Was it representative of the population? Were the questions unbiased?
Observation involves watching and recording what happens without interacting with subjects.
| Strength | Limitation |
|---|---|
| No interaction bias | Observer may influence behaviour |
| Real behaviour recorded | Can only observe what’s visible |
| Good for counting events | Time-intensive |
Measurement uses instruments to collect precise numerical data.
| Instrument | Measures | Unit |
|---|---|---|
| Ruler / tape measure | Length | mm, cm, m |
| Scales / balance | Mass | g, kg |
| Thermometer | Temperature | °C |
| Measuring jug | Volume/capacity | mL, L |
| Stopwatch | Time | s, min |
| Protractor | Angle | degrees |
Always record measurements with appropriate precision and units.
| What You Want to Know | Best Method |
|---|---|
| People’s opinions or preferences | Survey |
| How often an event occurs | Observation |
| A physical quantity (height, weight) | Measurement |
| Weather or environmental data | Measurement |
| Behaviour in a natural setting | Observation |
VCAA FOCUS: VCAA tasks may ask you to suggest an appropriate data collection method and justify your choice. Link your answer to the specific context given in the question.
