Mr. B, the manager of the retail store in Exercise 12. .44, has seen the effect month has on the mean number of customers per day and is now wondering about the effect day of the week has on the mean number of customers per day. Is the mean number of customers per day affected by the day of the week? Or equivalently, “Is the mean number of customers per day the same for all days of the week?” versus “Is there at least one day of the week when the mean number of customers per day is significantly different from that of the others?” The following computer output resulted from analysis of the data.
Inspect the preceding dotplot for number of customers per day for the six weekdays and the ANOVA output for number of customers versus day of the week. Look for evidence that leads to the conclusion “Not all days have the same mean number of customers per day.”
a. Describe the graphical evidence found and discuss how it shows that not all days of the week are the same. Which day or days appear to be different from the others?
b. Describe the meaning and source of the 5 points located to the right and separate from the rest of the data.
c. Describe the numerical evidence found and discuss how it shows that not all days are the same.
d. Can you tell which days are different based on the numerical evidence? Explain.
e. Use your calculator or computer to perform the ANOVA shown and verify the results.