ANOVA:Tukey Test, Weights of Poplar Trees & Secondhand Smoke

1. A researcher reports an F ratio with df = 2, 24 for an independent--‐ measure research study.
a. How many treatment conditions were compared in the study?
b. How many subjects participated in the entire study?

2. Posttests like a Tukey test are done after an analysis of variance.
a. What is the purpose for posttests?
b. Why wouldn't you do a posttest if the analysis was only comparing two treatments?
c. Why would you not do posttests if the decision from the ANOVA was to fail to reject the null hypothesis?

11--‐2 End of section exercises
3. Page 547 Do not complete exercise "e"

2. Weights of Poplar Trees. The chapter problem uses the weights of poplar trees for Year 1 and Site 1. If we use the weights for year 2and site 1, the analysis of variance results from SAS are as shown in the accompanying display (See the attachment). Assume that we want to use a 0.05 significance level in testing the null hypothesis that the four treatments result in weights with the same population mean.

a. What is the null hypothesis?
b. What is the alternative hypothesis?
c. Identify the value of the test statistic.
d. Find critical value for a 0.05 significance level.
e. Identify the P-value.
f. Based on the preceding results, what do you conclude about the equality of the population means?

4. Page 549 #10:

Secondhand Smoke in Different Groups. Refer to Data set 5 (see the attachment). Use a 0.05 significance level to test the claim that the mean cotinine level is different for these three groups: nonsmokers who are not exposed to environmental tobacco smoke, nonsmokers who are exposed to tobacco smoke and people who smoke. What do the result suggest about secondhand smoke?
See the data set in the attachment.

a. Show your ANOVA table, with all calculated values.
b. List df.
c. List critical values.
d. State conclusion: reject or do not reject null
e. Include an interpretive sentence or two.

5. Page 549#12:

Iris Petal Widths. Refer to Data Set 7 (see the attachment). Use a 0.05 significance level to test the claim that the three different species come from populations having the same mean petal width.

See the attachment for the data.

a. Show your ANOVA table, with all calculated values.
b. List df.
c. List critical values.
d. State conclusion: reject or do not reject null
e. Include an interpretive sentence or two.

See attached file.

Please show all work.