Statistics AS-Level

Simple Random Sampling

Every sample has an equal chance of being selected

Systematic Sampling

Required elements are chosen at regular intervals from an ordered list

Stratified Sampling

Population divided into mutually exclusive groups and a random sample is taken from each

Quota Sampling

Researcher selects a sample that reflects the characteristics of the whole population

Opportunity Sampling

Taking the sample from people available at the time the study is carried out and who fit the criteria

Quantitative Data

Numerical Observations

Qualitative Data

Non-numerical observations

Continuous Variable

Variable that can take any value in a given range

Discrete Variable

Variable can only take specific values in a given range

Population

Whole set of items that are of interest

Census

Measures every member of a population

Sampling Units

Individual units of a population

Sampling frame

list of sampling units

Sample

Observations taken from a subset of the population