sampling techniques (2)

  • Created by: tia5sos
  • Created on: 28-09-20 18:41
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  • sampling techniques (2)
    • you can also estimate population using capture - recapture
      • 1. capture a sample of the population and mark the animals in a harmless way.
      • 2. release them back into the environment.
      • 3. recapture another sample of the population, count how many of this sample are marked.
      • 4. the estimate the population using the equation highlighted
    • example:  pitfall trap was set up in an area of woodland. 30 woodlice were caught in an hour and marked on their shell, before being released back into the environment. The next day, 35 woodlice were caught in an hour, only 5 of which were marked. Estimate the population size..... (shown below)
    • when using the capture recapture method you have to make a number of assumptions.
      • these include;
        • there has been no change in the population size between the samples (births, deaths)
        • the marking hasn't affected individuals chance of survival (e.g. making them more visible to predators)


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