Use the following information to answer questions
1113
An ANOVA test is conducted to compare three different income tax
software packages to determine whether there is any difference in
the average time it takes to prepare income tax returns using the
three different software packages. Ten different individuals'
income tax returns are done by each of the three software packages
and the time is recorded for each. Because individual tax returns
are different the analysis has decided to block on individual
returns. The computer results are shown below. The level
of significance α = 0.05 for all tests. Complete the ANOVA
table as needed to answer the following questions.
SUMMARY

Count

Sum

Average

Variance

1

3

9

3

1

2

3

30

10

1

3

3

12

4

0

4

3

6.5

2.17

0.58

5

3

25

8.33

2.33

6

3

7

2.33

1.08

7

3

10

3.33

0.33

8

3

18

6

1

9

3

33.5

11.17

0.58

10

3

4.5

1.5

0.25






Software A

10

47.5

4.75

12.96

Software B

10

47.5

4.75

10.79

Software C

10

60.5

6.05

13.47

ANOVA
Source of Variation

SS

df

MS

F

F crit

Returns (Blocking)

329.91

9

36.66



Software






Error (within)

5.07

18










Total

346.25

29




 What is the calculated value of the F test statistic (select
the closest answer) for conducting the hypothesis test to determine
whether there is a difference in the software
packages?
 F = 2.46
 F = 3.55
 F = 130.93
 F = 20.11
 At the α = 0.05 level of significance what conclusions would
you make as to whether the type of software used has an effect on
the time required to complete individual tax returns?
 Because F calculated = 130.93 > F critical = 3.55 do not
reject the null hypothesis and conclude that type of software used
does not make a difference in average tax preparation time.
 Because F calculated = 20.11 > F critical = 3.55 reject the
null hypothesis and conclude that type of software used does make a
difference in average tax preparation time.
 Because F calculated = 2.46 is < F critical = 3.55, do not
reject the null hypothesis and conclude that type of software used
does not make a difference in average tax preparation time.
 No decision can be made as to whether the type of software used
makes a difference or not in average tax preparation time without
conducting a posttest comparison of all possible contrasts.
 Suppose in the tax preparation ANOVA problem above, a posttest
comparison is conducted to determine where differences exist
between all possible contrasts (all pairs) of software packages.
For this question focus only on the contrast between Software A and
Software C. If Fisher’s Least Significant Difference is
computed to be 0.497 then what conclusion would you make concerning
whether there is a significant different between Software A and
Software C?
 No conclusion can be reached unless a pooled ttest is
conducted.
 Because the absolute difference in sample means between
Software A and Software C is greater than Fisher’s Least
Significant Difference, we conclude the average tax preparation
time for the two software packages is equal.
 Because the absolute difference in sample means between
Software A and Software C is greater than Fisher’s Least
Significant Difference, we conclude the average tax preparation
time for the two software packages is different.
 The confidence interval for the difference between the two
software packages would need to include the value of 0 (zero) for
us to conclude that the average tax preparation time for the two
software packages is different.