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12 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Population |
A collection of objects, items, humans / animals ("units") about which information is sought. |
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Sample |
A part of the population that is observed. |
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Parameter |
A numerical characteristic of a population |
Percent unemployment in the US |
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Statistic |
A numerical function of the sample data, used to estimate an unknown parameter. |
Percent unemployment in a sample. |
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Sampling frame |
A list of all units in a finite population. |
Often, we do not have a sampling frame and we need to choose which units to sample. |
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Representative sample |
Does not differ in systematic and important ways from the population. |
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Convenience sampling |
Involves using a sample that is easily available. |
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Judgement sampling |
Involves a trained sample collector |
Bias is possible with these sampling methods. To avoid bias, sampled randomly from the population. |
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Simple random sample (SRS) |
Of size n from a population of size N |
Is drawn without replacement so that each possible sample of size n has the same chance of being chosen. |
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Stratified random sampling |
Involves dividing the population into homogeneous subpopulations and drawing and SRS from each one. |
This is useful when you want to do statistics on subpopulations as well as the whole population. e.g. customers stratified by race (some races are rarer than others) |
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Multi-stage cluster sampling |
"Tree structured" sampling. units are different at each stage. |
Useful for sampling large populations. |
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1 in k systematic sampling |
Consists of selecting every kth unit. |
Useful for sampling items coming off assembly lines. |
