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Aim: How do we test a comparison group

test hypotheses that compare means of two groups z test. Formula for the z Test for Comparing Two Means from Independent Populations. If you are comparing means, your will always equal 0 unless told otherwise. . Procedure. State the hypotheses and identify the claimFind the critical value(s)Compute the test valueMake the decision Summarize the results.

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Aim: How do we test a comparison group

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    1. Aim: How do we test a comparison group? Exam Tomorrow

    2. test hypotheses that compare means of two groups z test

    3. Formula for the z Test for Comparing Two Means from Independent Populations

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

    5. 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 a = 0.05, can it be concluded that there is significant difference in the rates?

    6. Solution State Hypothesis and identify claim Find critical value Calculate test value Make a decision Summarize the results

    7. test the difference between two variances F test

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

    9. Characteristics of the F Distribution The values of F cannot be negative, because variances are always positive or zero The distribution is positively skewed The mean value of F is approximately equal to 1 The F distribution is a family of curves based on the degrees of freedom of the variance of the numerator and the degrees of freedom of the variance of the denominator

    10. Steps State the hypothesis and identify claim Find the critical value Compare the test values Make the decision Summarize the results

    11. Example

    12. Solution

    13. test the difference between two means for small independent samples t test

    15. Use the t test when Option 1 Used when the variances of the populations are not equal Option 2 Use when the variances are equal

    16. Formula for the t test for testing the difference between two means of a small independent sample Variances are assumed to be unequal

    17. Formula for the t test for testing the difference between two means of a small independent sample Variances are assumed to be equal:

    18. Procedure Need to determine if the variances are equal if they did not give you any information about variances in the problem State the hypothesis Find the critical value (use f table) Compute test value with f test Make a decision Summarize results Decide which t test to use based on steps 1-5 State the hypothesis Find the critical values Compute test value with t test Make a decision Summarize results

    19. 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. Can it be concluded at a = 0.05 that the average size of the farms in the two countries is different? Assume the populations are normally distributed. Example

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