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KMID : 0356920150680060540
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Korean Journal of Anesthesiology
2015 Volume.68 No. 6 p.540 ~ p.546
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T test as a parametric statistic
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:Kim Tae-Kyun
저자없음:No authors listed
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Abstract
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In statistic tests, the probability distribution of the statistics is important. When samples are drawn from population N (μ, σ2) with a sample size of n, the distribution of the sample mean X? should be a normal distribution N (μ, σ2/n). Under the null hypothesis μ = μ0, the distribution of statistics z=X????μ0σ/n√z=X?-μ0σ/n should be standardized as a normal distribution. When the variance of the population is not known, replacement with the sample variance s2 is possible. In this case, the statistics X????μ0s/n√X?-μ0s/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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KEYWORD
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Biostatistics, Matched-pair analysis, Normal distribution, Probability
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