Starter quiz
- Capture-recapture is a sampling method which allows you to ______ the size of a population without counting it fully.
- 'estimate' ✓
- Jacob captures 10 birds and marks each one with some non-toxic dye. Jacob recaptures 10 birds, but finds that none of them have a paper band. Select the possible reasons for this.
- Jacob's sample size is too small. ✓
- The dye has washed off in the rain. ✓
- Jacob might have recaptured the same bird twice.
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- Which of these assumptions are made when the method of capture-recapture is used?
- The marked animals have mixed into the population so the recapture is random. ✓
- Some of new animals will have been born or migrated into the habitat.
- Some of the animals will have migrated or died.
- The popluation has remained constant. ✓
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- As part of a capture-recapture sample, 200 fish from a lake are captured and marked with a white dye. During a recapture of 100 fish, 12 were marked with the white dye. Select the correct statement.
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- ✓
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- Laura captures 9 deer and marks them by attaching a tag to their legs. Three days later, Laura recaptures 40 deer, and 4 of them have a tag attached. Estimate the total number of deer.
- '90' ✓
- Jun captures 21 squirrels and marks them by attaching a tag to their legs. Three days later, Jun recaptures 46 squirrels, and 7 of them have a tag attached. Estimate the total number of squirrels.
- '138' ✓
Exit quiz
- __________ can be present in any sample collected from a population and may affect the results of a statistical investigation.
- Bias ✓
- Discrete
- Randomness
- Strata
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- Laura flips a coin three times and it lands heads each time. Laura concludes the coin is biased. Is Laura correct?
- Yes, it is definitely biased.
- Yes, the chance of 3 heads in a row is very low.
- No, Laura needs to flip the coin 3 more times to be sure.
- No, Laura needs to flip the coin at least 100 more times. ✓
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- Izzy wants to find out what type of music is most popular among pupils at her school. She asks 5 of her friends who their favourite singer is. Which of these comments are correct?
- Izzy has a biased sample as her friends may like the same music. ✓
- 5 is too small a sample. ✓
- Izzy should ask more pupils from year 10.
- Izzy should ask some pupils from each year group. ✓
- Izzy should ask some teachers as well.
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Jacob and Sofia have both investigated what the favourite subject of the year 10 pupils in their school is. ______ sample is more likely to be representative of the population.- 'Sofia's' ✓
- Jacob and Sofia have both investigated what the favourite subject of year 10 pupils in their school is. Select the statements that are likely to be true.
- Jacob should have taken a larger sample. ✓
- Jacob had a good sampling method as his sample was more targeted.
- Jacob's sample was random.
- Sofia should have used a smaller sample.
- Sofia's sample was random. ✓
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Jun wants to find out if the town of Rowanwood needs a new sports centre. Comment on Jun's sampling method.- Jun's sample is too big.
- Jun's sample will be biased. ✓
- Jun shouldn't only ask people at the sports centre ✓
- Jun doesn't live in Rowanwood, so shouldn't ask there.
- Jun's enthusiasm may influence his results. ✓
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Worksheet
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Lesson Details
Key learning points
- A sample can only produce conclusions for that sample.
- A different sample may produce different conclusions.
- The usefulness of any conclusions may be limited by the sample size.
Common misconception
Samples always represent the population from which they are drawn as they come from that population.
Taking multiple large samples allows us to begin to generalise the results to the whole population.
Keywords
Sample - A sample is a subset of the population.
Bias - Bias can be present in any sample collected from a population and may affect the results of a statistical investigation.
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