3 terms

Stratified Sampling

Stratified Sampling
A method of probability sampling (where all members of the population have an equal chance of being included)

Population is divided into 'strata' (sub populations) and random samples are drawn from each

This increases representativeness as a proportion of each population is represented
Stratfied Sampling
Heatherton 1997
Heatherton et al (1997) measured changes in attitudes towards eating disorders with age;

They looked at 800 people;

400 males and 400 females

Half were senior students and half were freshman
Stratified Sampling
Strata's are expected to distinguish form each other

Another form of probability sampling is 'simple random sampling' but this is often difficult to achieve