AH Biology - Unit 3 - KA2(c) - Sampling

What is done when it’s not practical to measure every individual?

When it’s not possible to measure every individual, a representative sample of the population is selected.

What should a representative sample share with the population as a whole?

A representative sample should share the same mean and the same degree of variation about the mean as the population as a whole.

What is the size of a suitable sample determined by?

The size of a suitable sample is determined by the extent of the natural variation within that population.

What is the relationship between variability in a population and the sample size?

The relationship between variability in a population and sample size is that the more variable a population, the larger the sample size will need to be.

What are the three key types of sampling?

The three key types of sampling are:

• Random sampling

• Systematic sampling

• Stratified sampling

What is random sampling?

Random sampling is a type of sampling where members of the population have an equal chance of being selected. For example, throwing a quadrat.

What is systematic sampling?

Systematic sampling is a type of sampling where members of the population are selected at regular intervals. For example, a line or belt transect.

What is stratified sampling?

Stratified sampling is a type of sampling where the population is divided into categories and each one is sampled proportionally.