Doing Sociology: Research Methods — Sociology STD 11 Humanities — Question

A group of people that take part in a research investigation and are presumed to be representative of the population from which they have been drawn. Because of the constraints of time, money and practicality, psychologists can hardly ever study the whole population and therefore are forced to sample from it using one of the sampling methods.
Sampling: Refers to the process by which research psychologists attempt to select a representative group from the population under study. As an entire population tends to be too large to work with, a smaller group of participants must act as a representative sample. In an attempt to select a representative sample and thus avoid sampling bias (the over-representation of one category of participant in the sample), psychologists utilize a variety of sampling methods, such as:

1. Random Sample: Each member of the population under study stands the same chance of being selected.
2. Stratified Sample: The composition of the sample reflects the composition of the population, e.g. 30 percent males, 70 percent females in the population determines that the sample shall contain a selection of 70 percent females, 30 percent males.
3. Quota Sample: The researcher selects a quota of people roughly in proportion to their occurrence in the population (e.g. a quota of different age groups).
4. Opportunity Sample: Roughly a case of selecting whoever is available at the time at that location.