New
New
Year 10
Higher
Stratified sampling
I can carry out a stratified sample.
New
New
Year 10
Higher
Stratified sampling
I can carry out a stratified sample.
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.
Would it be fair to only survey one year group when considering food served in the school canteen? This question can be used to help pupils see that a representative sample may be biased but that intentional bias in a sample can be a good thing.
Teacher tip
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Video
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Starter quiz
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6 Questions
Q1.
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.
Q2.
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.
Q3.
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 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
Q4.
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?
Choosing the first six pupils who arrive at school
Choosing the first six names on the register
Q5.
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 .
Q6.
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#(1, 35)
RanInt#(1, 36)
RanInt#(11, 36)
Exit quiz
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6 Questions
Q1.
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
Mathematics
Q2.
A population may be split into groups or strata. A sample is where a representative sample is taken from each stratum.
Q3.
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
90 passengers and 10 crew
Q4.
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, 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
Q5.
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.
Q6.
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.