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Key Points
Used to estimate the size of a population.
A sample is captured, marked and released.
A second sample is captured and the number of marked items is counted.
Estimated population = (First sample × Second sample) ÷ Number of recaptured marked items.
Assumes the population is closed, markings remain visible, and marked individuals mix randomly before the second sample.
Keywords: capture-recapture, population estimate, sampling, probability, GCSE statistics.
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