alleryStart learning →What distinguishes a ratio from a proportion?
AA ratio's numerator need not sit inside its denominator
BA ratio must always be reported as a percentage figure
CA ratio can compare only two rates, never two counts
DA ratio always needs a multiplier of 100 or larger
Answer & Solution
Correct answer: A. A ratio's numerator need not sit inside its denominator
1. A ratio is the relative magnitude of two quantities, and the two quantities need not be related at all.
2. A proportion is a special kind of ratio in which the numerator is a subset of the denominator, so a part is compared with its whole.
3. Apples divided by oranges is therefore a ratio but not a proportion, while apples divided by all fruit is both.
4. Percentages, multipliers and the choice between rates and counts are presentation decisions, so none of them separates the two measures.
_Source: CDC Principles of Epidemiology in Public Health Practice (3rd ed., US federal, public domain), Lesson 3 "Measures of Risk", section Definition of proportion_
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