EC255 Lecture Notes - Lecture 10: Null Hypothesis, Confidence Interval, Standard Deviation
Document Summary
Ec255 chapter 10: statistical inferences about two populations. So far, we focused on inferences about a single population. But what about comparing per person expenditures on shoes in 2010 with those in 2008, and comparing market share of one company in two different regions. Goal: form a confidence interval for the difference between two population means, - Sample selected from one population has no effect on the sample selected from the other population and known. Population distributions are normal or both sample sizes are 30. Test statistic is a t value with (n1+ n2 2) degrees of freedom. The pooled estimate of the standard deviation is. Hypothesis tests for the difference between two means. The observed z value is: and unknown, equal. The observed t value with (n1+ n2 2) degrees of freedom is. An item in one sample is matched has something in common with an item in a second sample.
