Sampling Methods
There are four common sampling methods used in research. These sampling methods include: simple random sampling, systematic sampling, stratified sampling, and convenience sampling.
Simple Random Sampling: In simple random sampling, every sample of a given size has the same chance of being selected; this results in every individual of the population having an equal chance of being selected. Recall that random number generators are used to select samples. In the following figure, the random number generator selected numbers 24, 22, 27, 25, and 13, resulting in the highlighted individuals being selected for the sample.
[See the original DC page for how the images below need to convey the information]
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Video Placement
Simple Random Sampling – a very brief demonstration
Systematic Sampling: In systematic sampling, every individual in the population is given a number and individuals are chosen at regular intervals, with a random starting point (usually among the first several). The following figure illustrates a systematic sample where every 4th individual is selected, starting at the 3rd individual (starting point selected at random). The individuals selected for the sample are highlighted.
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Video Placement
Systematic Sampling – a very brief demonstration
Stratified Sampling: In stratified sampling, a population is divided into two or more groups (called strata) according to some criterion (i.e., geographic location, grade level, age group, income group, etc.), and a sample is selected from each strata using simple random sampling or systematic sampling.
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Video Placement
Stratified Sampling – a very brief demonstration
Convenience Sampling: A convenience sample is a sample of individuals who are most accessible to the researcher. A convenience sample is usually not random or representative of the population. This is an example of a biased sampling method because it has a tendency to produce samples that are not representative of the population. For example, you take a sample of your friends because it is easy to collect information about them.
Video Placement
Convenience Sampling – a very brief demonstration
