MGMT 1050 Chapter Notes - Chapter 14: Test Statistic, Statistical Hypothesis Testing, Weighted Arithmetic Mean
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13. 1: inferences about the difference between two means: independent samples. To estimate the difference between two population means, the statistics practitioner draws random samples from two populations (need to be normally distributed data) Best estimator of the difference between two population means (u1-u2) is the difference between two sample means (xbar1-xbar2) Note: these formulas are rarely used because the population variance is usually unknown: use degrees of freedom, standard error. Sp^2 = pooled variance estimator the weighted average of the two sample variances, with the number of degrees of freedom in each sample used as the weights. Cannot used the pooled variance estimator -degrees of freedom must be rounded down. How do we know when the population variances are equal: since population variances are unknown, need to perform a statistical test to see if the population variance differs, conduct the f-test of the ratio of two variances.
