期刊
KOREAN JOURNAL OF ANESTHESIOLOGY
卷 68, 期 6, 页码 540-546出版社
KOREAN SOC ANESTHESIOLOGISTS
DOI: 10.4097/kjae.2015.68.6.540
关键词
Biostatistics; Matched-pair analysis; Normal distribution; Probability
In statistic tests, the probability distribution of the statistics is important. When samples are drawn from population N (mu, sigma(2)) with a sample size of n, the distribution of the sample mean X-should be a normal distribution N (mu, sigma(2)/n). Under the null hypothesis mu = mu(0), the distribution of statistics z = X-mu 0/sigma/root n should be standardized as a normal distribution. When the variance of the population is not known, replacement with the sample variance s(2) is possible. In this case, the statistics X-mu 0/s root n follows a t distribution (n-1 degrees of freedom). An independent-group t test can be carried out for a comparison of means between two independent groups, with a paired t test for paired data. As the t test is a parametric test, samples should meet certain preconditions, such as normality, equal variances and independence.
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