A sample should connect to a defined population and a documented selection method. A large convenience sample can still be biased if important groups are missing.
Before you begin
Start with a small labeled table and clear units. Basic arithmetic is enough for the initial hand-worked exercise.
Work through the idea
Define the population, measurement and question before calculating. Show the actual values or counts used in the calculation and explain assumptions in plain language. Distinguish a descriptive observation from a causal claim. A small teaching example illustrates a method; it is not evidence about a real population.
- Define the target population
- Describe the sampling frame
- Compare random and stratified selection
Practice task
Design a fictional student survey with several course groups and different group sizes.
Check your result
Explain who can be selected, who may be missed and how nonresponse is recorded.
A mistake to avoid
Do not claim representativeness solely from a large response count.
Keep a review note
Save the inputs or scenario, your reasoning and the result you checked. Explain one assumption and one case that needs more work. Revise the exercise after feedback and distinguish what you demonstrated from what remains untested.
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