ENVS278 Chapter Notes - Chapter 21: Null Hypothesis, 2Degrees, Location Test
8 Oct 2016
School
Department
Course
Professor
Document Summary
The natural display for comparing two groups is box plots that are placed side by side should always start with them when comparing groups: helps to identify outliers. The population model parameter of interest is the difference between the mean batter lifetime of the two brands 1 2. The statistical interest is the difference in the two observed means y-bar1 y-bar2. Start by building the confidence interval need to know the standard deviation and its sampling model then we can build confidence interval and find p-values. We know that for independent random quantities the variance of their difference is the sum of their variances, var(y-x)= var(y)+var(x: sd (y-bar1-y-bar2) = [var(y-bar1 ) var (y-bar2)] However since we do not know the true standard deviations we will use estimates to get the standard error: se(y-bar1-y-bar2)= [(s2. Can use the standard error to see how big the difference really is (example p. 601)
