Starter quiz
- The population is the entire set of people, creatures, plants or items that make up the whole group which is being studied. A ______ is a subset of the population.
- 'sample' ✓
- A ______ sample is when a member or group are more or less likely to be chosen for a sample compared to other members of the population.
- 'biased' ✓
- Investigation: A scientist wants to check the biodiversity of plants and trees in Oak woods. What is the population in the scientist's investigation?
- All the plants and trees in the local area
- All the plants and trees in Oak woods ✓
- All the animals, plants and trees in Oak woods
- All the plants and trees near the paths in Oak woods
- All the plants and trees in all the woods
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- A teacher wants to select a simple random sample of six pupils from a class. Which of these can be used to generate a simple random sample?
- Assigning each pupil a number and using a calculator to generate random numbers ✓
- Assigning each pupil a number and using a computer to generate random numbers ✓
- Choosing the first six pupils who arrive at school
- Choosing the first six names on the register
- Putting all the names in a hat and randomly selecting six ✓
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These six pupils are assigned a range of numbers. A simple random sample of two pupils will be taken using these numbers. The range of integers that Jun should be assigned is ______.- '36 - 40' ✓
- These six pupils are assigned a range of numbers. A simple random sample of two pupils will be taken using these numbers. What calculation will generate a simple random sample for this population?
- RanInt#(1, 40)
- RanInt#(11, 40) ✓
- RanInt#(1, 35)
- RanInt#(1, 36)
- RanInt#(11, 36)
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Exit quiz
- A teacher wants to split the students at his school based on the strata of the modern foreign language they are studying. Select the appropriate strata.
- Art
- French ✓
- German ✓
- Mathematics
- Spanish ✓
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- A population may be split into groups or strata. A ______ sample is where a representative sample is taken from each stratum.
- 'stratified' ✓
- Select the sample that is most representative of the population from the given strata: A cruise ship with 2000 passengers and 500 crew. A sample of 100 people is taken.
- 50 passengers and 50 crew
- 60 passengers and 40 crew
- 70 passengers and 30 crew
- 80 passenger and 20 crew ✓
- 90 passengers and 10 crew
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- A company employs 250 band A workers, 350 band B workers and 200 Band C workers. A manager wants to take a stratified sample of 80 workers. How many workers from each band should be sampled?
- 20 band A, 35 band B and 25 band C
- 25 band A, 35 band B and 20 band C ✓
- 25 band A, 30 band B and 25 band C
- 25 band A, 40 band B and 15 band C
- 20 band A, 40 band B and 20 band C
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A bus company wants to take a sample of 500 customers, stratified by age. The table shows the number of customers in each age group. The bus company should choose ______ under-16s for the sample.- '151' ✓
- A bus company wants to take a sample of 500 customers, stratified by age. The table shows the number of customers in each age group. The bus company should choose ______ over 65s for the sample.
- '209' ✓
Worksheet
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Lesson Details
Key learning points
- A biased sample is not necessarily bad.
- You may wish to represent certain groupings in your sample.
- The sample from each group is proportional to the group size.
Common misconception
Stratified sampling is biased and therefore produces a bad sample.
Stratified sampling is used to take a representative sample from the population. Selecting from within the strata can be done using a simple random sample.
Keywords
Strata - A population may be split intro strata (groups). Each stratum is distinct and each item in the population can only belong to one stratum.
Stratified sample - A stratified sample is where a representative sample is taken from each stratum.
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