Sampling - A level Maths

simple random sampling

every member of the population has an equal probability of being selected for the sample

systematic sampling

select some starting point and then select every kth element in the population

stratified sampling

the population is divided into subgroups and weighted based on demographic characteristics of the national population

quota sampling

A nonprobability sampling technique in which researchers divide the population into groups and then arbitrarily choose participants from each group

opportunity sampling

A sample of participants produced by selecting people who are most easily available at the time of the study.

simple random sampling advantages

Free of bias

Each sampling unit has a known and equal chance of selection

simple random sampling disadvantages

A sampling frame is needed

systematic sampling advantages

Simple and quick to use

systematic sampling disadvantages

A sampling frame is needed

stratified sampling advantages

Sample accurately reflects the population structure

Guarantees proportional representation of groups within a population

stratified sampling disadvantages

Population must be clearly classified into distinct strata

Selection within each stratum suffers from the same disadvantages as simple random sampling

quota sampling advantages

No sampling frame needed

quota sampling disadvantages

Non-random sampling can introduce bias

Population must be divided into groups, which can be costly or inaccurate

Increasing scope of study increases number of groups, which adds time and expense

Non-responses are not recorded as such

opportunity sampling advantages

easy and inexpensive

opportunity sampling disadvantages

Unlikely to provide a representative sample