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Samples, Surveys, and Experiments (Vocabulary of Experiments (Experimental…
Samples, Surveys, and Experiments
Sampling Error
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Under-Coverage
groups that are part of the population you want to get information from are that left out of the sample
For example, only asking junior boys where next year’s prom should be. You are leaving out junior girls, seniors, and any underclassmen dates.
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Good Sampling Techniques
A simple random sample (SRS): Every individual within the total survey has an equal chance to be selected
An advantage of this technique is that the survey is chosen with everyone having a completely equal say.
A disadvantage of this technique is that it is much more time consuming, and therefore more expensive
Stratified SRS: the surveyor divides the population into groups of similar individuals (these groups are known as strata’s). Within each Strata the surveyor chooses an SRS and combines them together to form the complete survey.
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Cluster sampling: Choosing an SRS of small groups of the population. All the individuals chosen are included in the sample
An advantage of this form of sampling is that it is quick and easy. It also makes it easy to increase sample size.
The major disadvantage is that this is the least representative form of sampling, There is also a high sampling error.
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