Statistics QUESTIONS AND ANSWERS GRADE
A+
Explain what is meant by extrapolation. (1 mark)
Extrapolation is making predictions outside the original data range
Explain the dangers of extrapolation. (1 mark)
This is unreliable as the trend may not continue
The ornithologist attempts to calculate the product moment correlation
coefficient, r, and obtains a value of 1.3. Explain how she should be able to
identify that this is incorrect without carrying out any further calculations. (1
mark)
The product moment correlation coefficient cannot be greater than 1
Explain what is meant by a census.(1 mark)
Observation or measurement of every member of a population
Write down two disadvantages of using a census rather than a sample.(2 marks)
• takes a long time/costly
• difficult to ensure whole population surveyed
• cannot be used if the measurement process destroys the item
• can be hard to manage and analyse all the data
Each circuit board produced at GC Electronics is given a unique serial number.
GC Electronics produces circuit boards in batches of 5000. Before selling each
batch, the company tests a random sample of 20 circuit boards from the batch to
check that they will fit into a standard computer slot. Suggest a suitable sampling
frame from which to obtain this sample.(1 mark)
The list of unique serial numbers.
Each circuit board produced at GC Electronics is given a unique serial number.
GC Electronics produces circuit boards in batches of 5000. Before selling each
batch, the company tests a random sample of 20 circuit boards from the batch to
, check that they will fit into a standard computer slot.
Identify the sampling units.(1 mark)
A circuit board.
Explain what is meant by the word 'population'.(1 mark)
A complete collection of relevant individual people or items.
Jo needs to conduct a survey to investigate the type of kitchen cleaner people
prefer. She wants a random sample of people who use kitchen cleaners. She
decides to stand in a busy high street on a Saturday afternoon and attempt to get
shoppers to answer her questions.
State the sampling technique Jo has used.(1 mark)
Opportunity (convenience)
Jo decides to look at the electoral register for a town and selects a sample of 50
households to contact. She decides to select every 10th name on the electoral
register to add to her sample.
State the sampling technique Jo has used.(1 mark)
Systematic
Jo decides to look at the electoral register for a town and selects a sample of 50
households to contact. She decides to select every 10th name on the electoral
register to add to her sample.
Give two reasons why Jo may again be unsuccessful getting the data required
using this sampling technique.(2 marks)
• not random
• electoral register may have errors
• there may not be enough (500) households on the register
Before redecorating the school canteen the headteacher decided to survey the
opinion of staff and students.
Explain why the headteacher decided to take a stratified sample of staff and
students.(1 mark)
• to obtain a representative sample
• large number of students compared to staff so would be unfair to take same numbers
of both
A+
Explain what is meant by extrapolation. (1 mark)
Extrapolation is making predictions outside the original data range
Explain the dangers of extrapolation. (1 mark)
This is unreliable as the trend may not continue
The ornithologist attempts to calculate the product moment correlation
coefficient, r, and obtains a value of 1.3. Explain how she should be able to
identify that this is incorrect without carrying out any further calculations. (1
mark)
The product moment correlation coefficient cannot be greater than 1
Explain what is meant by a census.(1 mark)
Observation or measurement of every member of a population
Write down two disadvantages of using a census rather than a sample.(2 marks)
• takes a long time/costly
• difficult to ensure whole population surveyed
• cannot be used if the measurement process destroys the item
• can be hard to manage and analyse all the data
Each circuit board produced at GC Electronics is given a unique serial number.
GC Electronics produces circuit boards in batches of 5000. Before selling each
batch, the company tests a random sample of 20 circuit boards from the batch to
check that they will fit into a standard computer slot. Suggest a suitable sampling
frame from which to obtain this sample.(1 mark)
The list of unique serial numbers.
Each circuit board produced at GC Electronics is given a unique serial number.
GC Electronics produces circuit boards in batches of 5000. Before selling each
batch, the company tests a random sample of 20 circuit boards from the batch to
, check that they will fit into a standard computer slot.
Identify the sampling units.(1 mark)
A circuit board.
Explain what is meant by the word 'population'.(1 mark)
A complete collection of relevant individual people or items.
Jo needs to conduct a survey to investigate the type of kitchen cleaner people
prefer. She wants a random sample of people who use kitchen cleaners. She
decides to stand in a busy high street on a Saturday afternoon and attempt to get
shoppers to answer her questions.
State the sampling technique Jo has used.(1 mark)
Opportunity (convenience)
Jo decides to look at the electoral register for a town and selects a sample of 50
households to contact. She decides to select every 10th name on the electoral
register to add to her sample.
State the sampling technique Jo has used.(1 mark)
Systematic
Jo decides to look at the electoral register for a town and selects a sample of 50
households to contact. She decides to select every 10th name on the electoral
register to add to her sample.
Give two reasons why Jo may again be unsuccessful getting the data required
using this sampling technique.(2 marks)
• not random
• electoral register may have errors
• there may not be enough (500) households on the register
Before redecorating the school canteen the headteacher decided to survey the
opinion of staff and students.
Explain why the headteacher decided to take a stratified sample of staff and
students.(1 mark)
• to obtain a representative sample
• large number of students compared to staff so would be unfair to take same numbers
of both
