Description
1. (Chapter 10, Section 10.1, Exercise 6. “Origin of Precambrian Iron Formations”) Carry
out the ANOVA to investigate if the average Fe percentage for any of the four iron
formations is different.
a. How many treatments are there? How many replications for each treatment?
b. State the null and alternative hypothesis for the average Fe percentage for any of the
four iron formations.
c. Construct the ANOVA table using the summary statistics provided below. (You can
also use R software. The dataset “iron” is on blackboard.)
∑∑𝑥𝑖𝑗
2 = 33882.24
d. Make a decision about the test and interpret.
e. Do the following diagnostic plots suggest that the model assumptions are
inappropriate? Justify each assumption separately.
Treatment Mean
Carbonate 𝑥̅1. = 26.08
Hematite 𝑥̅2. = 33.84
Magnetite 𝑥̅3. = 29.95
Silicate 𝑥̅3. = 24.69
2. An experiment was run to compare 𝑰 = 𝟑 types of boxes (treatment) with respect to
compression strength. Each treatment is replicated 7 times.
a. Complete the ANOVA table by filling in the blanks with the correct values.
Source Df SS MS F P-Value
Treatment 0.0668
Error 0.0151
Total
b. Let i be the true average compression strength for box type 𝑖 = 1, 2, 3. Construct the
Tukey’s interval for each pair of the i-j. Use the
sample mean from the table.
c. Apply the T Method and draw the underscore plot for comparing the treatments. Briefly
explain your results.
