1C Population, sample and sampling

Population: the group of people who are the focus of the research and from which the sample is drawn

Sample: a subset of the research population who participate in a study

• Generalisability: the ability for a sample’s results to be used to make
• conclusions about the wider research population

Sampling technique: The way a sample is selected from the population for a study

• Three sampling techniques:
• • convenience sampling
• • random sampling
• • stratified sampling.

Convenience sampling refers to selecting readily available members of the population, rather than using a random or systematic approach.

• Advantages:
• - most time-effective and cost-effective

• Disadvantages:
• - most likely to produce an unrepresentative sample
• - harder to generalise results to population

• Random sampling refers to the use of a procedure to ensure every
• member of the population has the same chance of being selected.

• Advantages:
• - sample more representative than convenience
• - reduces experimenter bias in the selection
• - create a fairly representative sample if sample is large

• Disadvantages:
• - time-consuming to ensure each memeber of population has equal chance of selection for sample
• - may not create entirely representative sample if sample is small

• Stratified sampling involves selecting people from the population
• in a way that ensures that its strata (subgroups) are proportionally represented in the sample.

• Advantages:
• - most likely to produce a representative sample

• Disadvantages:
• - time-consuming and expensive
• - demanding on researcher to select most appropriate strata to account for

Allocation is the process of assigning participants to experimental conditions or groups.

Random allocation ensures every sample participant has an equal chance of being allocated to any group within the experiment.