In: Statistics and Probability
How productive are U.S. workers? One way to answer this question is to study annual profits per employee. A random sample of companies in computers (I), aerospace (II), heavy equipment (III), and broadcasting (IV) gave the following data regarding annual profits per employee (units in thousands of dollars).
| I | II | III | IV | 
| 27.2 | 13.3 | 22.9 | 17.2 | 
| 23.3 | 9.8 | 20.2 | 16.6 | 
| 14.4 | 11.7 | 7.8 | 14.1 | 
| 8.7 | 8.2 | 12.2 | 15.9 | 
| 11.5 | 6.3 | 7.9 | 10.1 | 
| 19.3 | 9.4 | 
Shall we reject or not reject the claim that there is no difference in population mean annual profits per employee in each of the four types of companies? Use a 5% level of significance.
(a) What is the level of significance?
(b) Find SSTOT, SSBET, and SSW and check that SSTOT = SSBET + SSW. (Use 3 decimal places.)
| SSTOT | = | |
| SSBET | = | |
| SSW | = | 
Find d.f.BET, d.f.W,
MSBET, and MSW. (Use 3 decimal
places for MSBET, and
MSW.)
| dfBET | = | |
| dfW | = | |
| MSBET | = | |
| MSW | = | 
Find the value of the sample F statistic. (Use 3 decimal
places.)
What are the degrees of freedom?
(numerator)
(denominator)
(c) Make a summary table for your ANOVA test.
| Source of Variation  | 
Sum of Squares  | 
Degrees of Freedom  | 
MS | F Ratio  | 
P Value | Test Decision  | 
| Between groups | ||||||
| Within groups | ||||||
| Total |