Practice question · Multiple choice
A researcher could match two groups carefully on age, sex and income, or assign at random. Randomisation usually wins. Why prefer chance over deliberate care?
Hints
- List the variables you would match on. Now ask what is not on your list.
- The threat to a causal claim is usually the confounder you did not consider.
Show the answer
B. Because matching only equates the variables you thought of
Why
Matching handles your list; randomisation handles the list you could not write. That is the whole of its power, it neutralises unmeasured and unimagined differences at once, which no amount of care about age and income can do.
Practise Experimental Design
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