Chapter 5 Flashcards
Sampling
The process by which a reasearcher selects a sample of participants for a study
Probability sample
A sample that is selected in such a way that the likelyhood that any individual int he population will be selected for the sample can be specified
Simple random sample
Every possible sample of a desired size has the same chance of being selected from the population and, by extension, every individual in the population has an equal chance of being selected for the sample
Representative sample
One from which we can draw accurate, unbiased estimates of the characteristics of a larger population
Sampling error
The characteristics of the individuals selected for the sample always differ somewhat format he characteristics of the general population
Error of estimation/margin of error
The degree to which the data obtained for the sample are expected to deviate format he popualation as a whole
Probability sample
A sample for which a researcher knows the mathematical probability that any individual in the population is included in the sample
Sampling frame
A list of the population form which the sample will be drawn
Table of random numbers
Contains long rows numbers that have been generated in a random order and is used for simple random sampling
Systematic sampling
Taking every so many individuals for the sample
Stratafied random sampling
A variation of simple random sampling in which the population is divided into two or more subgroups or strata and cases are randomly sampled form each of the strata
Stratum
The subset of the population that shares are particulate characteristic
Proportionate sampling method
Cases are sampled from each stratum in porportion to their prevelance in the population
Cluster sampling
The researcher samples groupings or clusters of participants
Multistage cluster sampling
A researcher begins by random sampling large clusters, then smaller clusters form within those large clusters, then sample even smaller clusters, and finally obtains his/her sample of participants
4 Types of probability sampling
- Simple random sampling
- systematic sampling
- statified random sampling
- cluster sampling
Nonresponse problem
The failure to obtain responses from individuals whom researchers select for a sample
Misgeneralization
Results may be misleading if the researcher generalizes them to a population that differs from the one from which the sample was obtained
Nonprobabilty samples
Researchers have no way fo knowing the probability that a particulate case will be chosen for a sample
3 types of nonprobability samples
- Convenience
- quota
- Purposive
Convenience sample
Includes participants that are readily available
Quota sample
Convenience sample in which the reasearcher takes steps to insure that certain kinds of participants are obtained in particular proportions
Purposive sample
Researchers use past research findings or their judgment to decided which participants to include in the sample, trying to choose respondents that are typical in the population they want to study
Power
The ability of a research design to detect any effects of the variables being studied that exist in the data
