What Is a Test Sample?
Politicians and news organizations frequently conduct opinion polls to determine how a certain segment of the population feels about a specific topic or idea. Interviewing everybody is never possible, so a small portion of the population is asked to give their opinion. Statistical analysis is then applied to the small sample to determine the accuracy of the result.
Other People Are Reading
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Test Sample Defined
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A test sample refers to a small group taken from a larger group for the purpose of conducting an experiment. The small group must be of a significant size so that responses to a specific stimulus or experiment are statistically the same as that of the larger group.
What Is a Statistic?
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A statistic is the application of a numerical value to a specific piece of data. For example, a sample piece of data might involve the number homeowners who own cats. One statistic might be the number of people in a given sample who own both a house and a cat.
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Parameter
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The parameter is a piece of data to which the value is unknown. Using the above example we might want to know how many homeowners in the city of Pittsburgh own a cat.
Choosing a Sampling
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The size of our sampling may be limited by time and manpower available for conducting the sampling. Still, we will want to conduct a sample large enough to obtain a dependable result. Asking 20 homeowners is better than asking just two owners. Asking 200 is better than 20, and so on.
Sampling Error
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No sampling percentage is perfectly accurate. The degree of accuracy is estimated by calculating a sampling error for our survey. If we survey just two people, our sampling error will be very high, but if we ask 20,000 people our sampling error will be much lower.
Law of Diminishing Return
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If we ask 2,000 people, our sampling error may not be much different than if we ask 20,000 people. This depends on several variables, but finding the optimum size of the test sample is of major importance in statistics.
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References
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