Data Collection

Scheme of work: Year 12 A-Level: Applied: Statistics: Data Collection

Infer properties of populations or distributions from a sample while knowing the limitations of sampling
Apply statistics to describe a population
Design a questionnaire without bias
Understand the difference between quantitative and qualitative data
Calculate the mean, mode and median from a frequency table.

Understand and use the terms population and sample.
Use samples to make informal inferences about the population
Understand and use sampling techniques, including simple random sampling and opportunity sampling.
Select or critique sampling techniques in the context of solving a statistical problem, including the understanding that different samples can lead to different conclusions about the population

Students need a good understanding of the keywords:
Population, census, sample, sampling unit, sampling frame, simple random sampling, stratified, systematic, quota, opportunity (convenience) sampling, and how to apply these within a real-world problem.
Students could practise applying these keywords as an introduction to the large dataset.
When comparing the different types of sampling, students should consider each method’s advantages and disadvantages regarding cost, time, complexity and other real-world implications.

Students often struggle to explain how to design a sampling frame within the context of the problem.
When asked to describe how to select a random sample, students sometimes write lengthy responses that lack specificity. Instead, answers should focus on designing the sampling frame, such as assigning each population member a unique ID.
While most students can calculate a stratified sample, they sometimes struggle to describe why a stratified sample within the context of the question.
Students often struggle to describe the difference between a quota and stratified sampling, mainly when each is more suited to the context of the question.
Students often quote textbook definitions to define terms such as population, sample, stratified, and randomisation when answering exam-style questions. However, they should instead explain how these definitions related to the real-life situation stated in the context of the question.

Data Collection Resources