A population may be split intro strata (groups). Each stratum is distinct and each item in the population can only belong to one stratum.

A stratified sample is where a representative sample is taken from each stratum.

Stratified sampling

Maths

In this unit, pupils are given the opportunity to assess how valid a sample may be and what the averages might tell us. In the future unit, pupils extend their knowledge of averages to stem and leaf diagrams as well as comparing two data sets.

In the prior unit, pupils considered the mean, median and mode and evaluated their usefulness in a variety of contexts. In this unit, pupils are given the opportunity to consider where the data came from and how it was collected and can therefore start to evaluate how good a representation the sample is of the whole population.

Sampling

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.

A population may be split into groups or strata. A {{}} sample is where a representative sample is taken from each stratum.  

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.

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? 

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.

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.

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.

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. 

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

Investigation: A scientist wants to check the biodiversity of plants and trees in Oak woods. What is the population in the scientist's investigation?

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

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?

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 {{}}.

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?

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