What you'll learn
The stages every statistical investigation follows.
The four stages
- Specify the problem and plan: state a clear hypothesis and decide what data to collect.
- Collect data: choose a source (primary or secondary) and a sampling method.
- Process and represent data: calculate summaries (averages, spread) and draw suitable charts.
- Interpret and discuss: draw conclusions, evaluate the method and refine the hypothesis.
The cycle is iterative — findings often lead back to a new hypothesis.
Key terms
- Hypothesis: a statement to be tested.
- Primary data: collected first-hand; secondary data: from existing sources.
- Qualitative (categories) vs quantitative (numerical, discrete or continuous) data.
Exam tips
- Write hypotheses that are specific and testable.
- Always evaluate limitations of the method in the final stage.
Common mistakes
- Skipping the planning stage in longer questions.
- Confusing qualitative with quantitative data.