Sampling and Generalizability

Snowball sampling

A method of sampling in which sample elements are selected as they are identified by successive informants or interviewees

Systematic random sampling

A method of sampling in which sample elements are selected from a list or from sequential files

Stratified Random Sampling

A method of sampling in which sample elements are selected separately from population strata that are identified in advance by the researcher

Random sampling

A method of sampling that relies on a random, or chance selection method so that every element (participant) has an equal chance of being selected

Purposive sampling

A nonprobability sampling method in which elements are selected for a purpose, usually because of their unique position

Quota Sampling

A nonprobability sampling method in which elements are selected to ensure that the sample represents certain characteristics in proportion to their prevalence in the population.

Representative sample

A sample that 'looks' like the population from which it was selected in all respects that are potentially relevant to the study

Probability sampling

A sampling method that relies on a random, or chance selection method so that the probability of selection of population elements is known

Sample

A subset of a population that is used to study the population as a whole

Generalizability

Exists when a conclusion holds true for the population, group, setting, or event that we say it does, given the conditions that we specify

Cross population generalizability

Exists when findings about one group, population, or setting hold true for other groups, populations or settings

Census

Research in which information is obtained through the responses that all available members of an entire population give to the questions

Availability Sampling

Sampling in which elements are selected on the basis of convenience

Nonprobability sampling

Sampling method of which the probability of selection is population elements is unknown

Population

The entire set of individuals or other entities to which study findings are to be generalized

Probability of selection

The likelihood that an element will be selected from the population for inclusion in the sample

Sample generalizability

exists when a conclusion based on a sample, or subset, of a larger population holds true for that population

Sampling theory

focuses on the generalizability of descriptive findings to the population from which the sample was drawn; also considers whether statements can be generalized from one population to another

sampling error

the difference between the characteristics of a sample and the characteristics of the population from which it was selected

Meanings of Generalizability

• can the findings be generalized to the population being sampled? • can the findings be generalized to another population? Sampling generalizability depends on sample quality determined by - sampling error