BUSS1020 Lecture Notes - Lecture 10: Null Hypothesis, Standard Deviation, Test Statistic

• School: University of Sydney
• Department: Business Studies
• Course: BUSS1020
• Professor: Erick Li

Document Summary

Lecture 10 - hypothesis testing: two sample (textbook chapter 10) As d. f. increases, the critical value decreases and vice versa. In almost all cases, you would not know the standard deviation of the population under study. Likewise, when you take a random sample from each of two independent populations, you almost always do not know the standard deviation of either population. In addition, when using a two-sample test that compares the means of samples selected from two populations, you must establish whether the assumption that the variances in the two populations are equal holds. The statistical method used to test whether the means of each population are different depends on whether the assumption holds or not. Pooled-variance t-test for the difference between two means: If the populations do not differ greatly from a normal distribution, you can still use the pooled-variance t test, especially if the sample sizes are large enough (typically 30 for each sample).