Aim How do we test a comparison group

Aim: How do we test a comparison group? Review QUIZ TOMORROW

test hypotheses that compare means of two groups

Formula for the z Test for Comparing Two Means from Independent Populations If you are comparing means, your otherwise. will always equal 0 unless told

Procedure 1. State the hypotheses and identify the claim 2. Find the critical value(s) 3. Compute the test value 4. Make the decision 5. Summarize the results

Example • A survey found that the average hotel room rate in New Orleans is $88. 42 and the average room rate in Phoenix is $80. 61. Assume the data were obtained from two samples of 50 hotels each and the standard deviations were $5. 62 and $4. 83, respectively. At α = 0. 05, can it be concluded that there is significant difference in the rates?

Solution 1. State Hypothesis and identify claim 2. Find critical value 3. Calculate test value 4. Make a decision Test value > critical value (reject null) 5. Summarize the results There is enough evidence to support the claim that the means are not equal to each other

test the difference between two variances

Formula for the F Test • The larger of the two variances is placed in the numerator regardless of the subscripts

Steps 1. 2. 3. 4. 5. State the hypothesis and identify claim Find the critical value Compare the test values Make the decision Summarize the results

Example • The average size of a farm in Indiana County, Pennsylvania, is 191 acres. Assume the data were obtained from two samples with standard deviations of 38 and 12 acres, respectively, and sample sizes of 8 and 10, respectively. Using α = 0. 05, is there enough evidence to support the claim that the variances are equal?

Solution

Review for Quiz • Complete Worksheet