Statistics Assignment Help>> T Test, z-Test, Chi-Square Test Assignment Help

t检验

t检验can be said to be the statistical hypotheses test where the test statistic follows the student’s t distribution when the null hypotheses is not supported. It’s most common application is in the test statistic following normal distribution where values of scaling terms of test static’s are known. In case the scaling terms are unknown and are replaced by the estimates which are based on data, then the test statistics under certain conditions does follows a student’s t distribution. The t statistics were introduced in the year 1908 by a chemist name William Seasly Gusset, in Dublin, Ireland. He devised the test as a way for cheaply monitoring the qualities of stouts. The t-test are used in

1.一个样本测试位置finding out the mean of normally distributed populations as signified in the null hypotheses.

2. A two sample location test of null hypothesis where the means of two normally distributed populations are found equal. These tests are also termed as student’s test.

3. The test for whether the slope of regression line is in significant difference from zero.

Z检验

A statistical test for which the distribution of the statistic of the test, which is under the null hypotheses, can be approximated by using a normal distribution and is termed as z-test. The approximated z tests are mostly performed for larger sample sizes, because as per the central limit theorem, many of the test statistics are approximately normally distributed for only the large samples.

Z-test is used for one sample location tests for comparing the mean of given constant’s sets of measurements. When the observed data X₁, ..., An are uncorrelated, contain a common mean μ, and also have the common variance of σ², sample average X has the mean μ and the variance σ²/ n。对于以给定数量μ的平均值为μ的零假设₀, X −μ₂can be used as the test-statistic. If X −μ₀is large, the null hypotheses can be rejected.

Z test are applicable in the below given conditions

1.The nuisance parameters must be known or must be estimated with high accuracy as the z tests only focus on single parameters while treating the other unknown parameters having fixed true values.

2. A normal distribution must be followed by the test statistic.

The Chi-Square test

在这种类型的统计假设检验中，当零假设为真或零假设不正确时，采样分布是CHI方形分布。这意味着通过增加样品的大小，可以非常接近采样分布（达到欲望的程度）。皮尔逊的卡方检验，通过运动卡方测试线性线性，耶茨卡方检验，可能性卡方检验是卡方检验的一些示例。

当测试统计量的分布是给定种群的方差具有给定值的测试时，卡方分布可以准确地确切，这是基于样本方差的。这些测试在实际实践中很少见，因为要测试的方差值很少以确切的方式知道。

当我们获取具有正态分布的人群的大小n的样本时，我们将获得已知的结果。可以根据其人口的差异确定该测试是否具有预确定的值。

Live Statistics Experts: t-Test, z-Test Analysis Assignment Help

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