AI generatedStatisticsGCSE Foundation / IGCSE Core

Systematic sampling

Systematic sampling.

Named sampling methods vary by course. Check your specification or teacher’s guidance.

  • Sampling interval = population size ÷ sample size, when this is a whole number.
  • Choose a random start within the first interval, then take every kth member.
  • Check for a repeating pattern in the list that matches the interval.

Example 1

There are 20 names in a list. Select a systematic sample of 5, using the randomly chosen start 1. Give the selected positions.

Sampling intervalDivide the population size by the required sample size.
PositionsStart at the given random position, then add the interval each time.
Select these 5 positions. In a full procedure, choose the start randomly from 1 to 4.

Check the list has no repeating pattern matching the interval. A systematic sample is not the same as a simple random sample.

Example 2

There are 24 names in a list. Select a systematic sample of 6, using the randomly chosen start 2. Give the selected positions.

Sampling intervalDivide the population size by the required sample size.
PositionsStart at the given random position, then add the interval each time.
Select these 6 positions. In a full procedure, choose the start randomly from 1 to 4.

Check the list has no repeating pattern matching the interval. A systematic sample is not the same as a simple random sample.

Your turn

Question 1

There are 28 names in a list. Select a systematic sample of 7, using the randomly chosen start 3. Give the selected positions.

Check answer
Sampling intervalDivide the population size by the required sample size.
PositionsStart at the given random position, then add the interval each time.
Select these 7 positions. In a full procedure, choose the start randomly from 1 to 4.

Check the list has no repeating pattern matching the interval. A systematic sample is not the same as a simple random sample.

Question 2

There are 32 names in a list. Select a systematic sample of 8, using the randomly chosen start 4. Give the selected positions.

Check answer
Sampling intervalDivide the population size by the required sample size.
PositionsStart at the given random position, then add the interval each time.
Select these 8 positions. In a full procedure, choose the start randomly from 1 to 4.

Check the list has no repeating pattern matching the interval. A systematic sample is not the same as a simple random sample.

Question 3

There are 36 names in a list. Select a systematic sample of 9, using the randomly chosen start 1. Give the selected positions.

Check answer
Sampling intervalDivide the population size by the required sample size.
PositionsStart at the given random position, then add the interval each time.
Select these 9 positions. In a full procedure, choose the start randomly from 1 to 4.

Check the list has no repeating pattern matching the interval. A systematic sample is not the same as a simple random sample.

Question 4

There are 40 names in a list. Select a systematic sample of 10, using the randomly chosen start 2. Give the selected positions.

Check answer
Sampling intervalDivide the population size by the required sample size.
PositionsStart at the given random position, then add the interval each time.
Select these 10 positions. In a full procedure, choose the start randomly from 1 to 4.

Check the list has no repeating pattern matching the interval. A systematic sample is not the same as a simple random sample.

Question 5

There are 25 names in a list. Select a systematic sample of 5, using the randomly chosen start 2. Give the selected positions.

Check answer
Sampling intervalDivide the population size by the required sample size.
PositionsStart at the given random position, then add the interval each time.
Select these 5 positions. In a full procedure, choose the start randomly from 1 to 5.

Check the list has no repeating pattern matching the interval. A systematic sample is not the same as a simple random sample.

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