Maths - Statistical sampling

What is data?

Data is pieces of information collected for an investigation.

What is a population?

A population is all the available data

What is a sample?

A sample is a part/ section of the data available.

What is a sampling frame?

A sampling frame is a list or dataset of all members of a specific population from which a sample can be drawn.

What are the pros of simple random sampling?

It is free of bias

easy to implement for small populations and small samples.

What are the cons of simple random sampling?

Not suitable for large samples or large populations.

A sampling frame is needed.

What are the pros of systematic sampling?

Simple and quick to use

suitable for large samples and population sizes

What are the cons of systematic sampling?

A sampling frame is needed.

It can introduce bias if the sampling frame is not random.

What are the pros of stratified sampling?

The sample accurately reflects the population structure.

It guarantees proportional representation of groups within a population.

What are the cons of stratified sampling?

Population must be clearly classified into distinct strata.

Each selection within each individual strata suffers the same disadvantages as simple random sampling.

What are the pros of opportunity sampling?

Easy to carry out.

It is inexpensive.

What are the cons of opportunity sampling?

It is unlikely to provide a representative sample.

It is highly dependent on the individual researcher.

What are the pros of quota sampling?

It allows a small sample to still be representative of the population.

No sampling frame is needed.

It is quick, easy and cheap to carry out.

What are the cons of quota sampling?

Non-random sampling can introduce bias.

population must be divided into groups which can be costly or inaccurate.

Increasing the scope of study increases the number of groups which are represented which adds time and expense.