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GCSE Combined Science · key term
Choosing sample locations by chance rather than personal preference, to reduce selection bias.
Used by AQA and Edexcel
Specification 4.7.2.1 · Paper 2
Revise: Ecological Sampling and Data AnalysisRandom sampling is useful for estimating abundance across an area. To investigate how distribution changes across a habitat, use a transect: a line along which samples are taken. A line transect can record species touching the line; placing quadrats at regular intervals also records abundance in a known area beside it.
Paper 1, Paper 2
Selecting sampling locations by chance rather than choosing them deliberately, to reduce selection bias.
Revise: Ecological Fieldwork and Population EstimatesRandom sampling helps estimate population size across an area. A belt transect investigates distribution: how the number of organisms changes from one part of a habitat to another, perhaps as light intensity changes.
Describe random sampling precisely: generate random coordinates and place the quadrat at those coordinates. Throwing a quadrat is not a reliable random method.
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