4.7.2

Quantitative Investigation

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Investigating Variation

The variation within a habitat can be measured in a quantitative investigation. To ensure the results from the investigation are accurate, the following practices should be used:

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Random sampling

  • Random sampling investigates the variation in a population without spending hours counting every individual.
  • Random sampling ensures the sample accurately represents the total variation of the species.
  • Random sampling is applied by assigning individuals numbers and randomly selecting the numbers using a computer program.
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Calculating the mean

  • The mean provides an average for all the values collected.
  • The mean is calculated in the equation:
    • mean = Σ  allindividualvaluesnumberofvalues\frac{\Sigma \; all individual values}{number of values}
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Standard deviation

  • Standard deviation shows how far away the values are from the mean average.
  • Standard deviation (SD) is calculated in the equation:
    • SD = Σ  (individualvaluemeanforallthevalues)2numberofmeanvalues\sqrt {\frac{\Sigma \; (individual value - mean for all the values)^2}{number of mean values}}

Jump to other topics

1Biological Molecules

2Cells

3Substance Exchange

4Genetic Information & Variation

5Energy Transfers (A2 only)

6Responding to Change (A2 only)

7Genetics & Ecosystems (A2 only)

8The Control of Gene Expression (A2 only)

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