표본추출과 추정 용어정리

Simple random smpling
a method of selecting a sample in such a way that each item or person in the population being studied has the same likelihood of being included in the sample.

Sampling error
the difference between a sample statstic (the mean, variance, or standard deviation of the sample) and its corresponding population parameter (the true mean, variance, or standard deviation of the population)

Sampling disturibution
a probability distribution of all possible sample statstics computed from a set of equal-size samples that were randomly drawn from the same population.

Stratified random sampling
a classification system to separate the population into smaller groups based on one or more distinguising characteristics.

Standard error of the sample mean
the standard deviation of the distrubution of the sample means.

when the standard deviation of the population, ∝, is known, the standard error of the sample mean is calculated as ∝/√n


Power of a test
the probability of correctly rejecting the null hypothesis when it is false.
=1-P(Type2 error)

P-value
the probability of obtaining a test statistic that would lead to a rejection of the null hypothesis, assuming the null hypothesis is true. It is the smallest level of significance for which the null hypothesis can be rejected.