252grass4-0414/02/04Name, Student Number:

(Open this document in 'Page Layout' view!)Class days and time:

Please include this on what you hand in!

Graded Assignment 4

The data set is part of a problem due to Pelosi and Sandifer.

20 Employees (A-T) are timed in a computer entry task initially (0hr), after 2 hours of work (2hr), after 4 hours (4hr) and after 6 hours (6hr). The times, in seconds are reported below.a) At a 5% significance level do the four mean times differ? b) determine which of the times actually differ. c) On the basis of these data, how would you react to a proposal that employees only be allowed to work for four hours a day at this task?Only neat and legible papers with written answers in complete sentences will be read!

0 Hours 2 Hours 4 Hours 6 Hours
67 / 84 / 52 / 57
64 / 78 / 53 / 53
69 / 74 / 56 / 71
88 / 91 / 66 / 61
72 / 70 / 59 / 73
80 / 73 / 77 / 50
85 / 86 / 64 / 53
116 / 71 / 62 / 80
77 / 76 / 54 / 63
78 / 76 / 65 / 41
68 / 61 / 71 / 63
51 / 62 / 92 / 41
54 / 94 / 71 / 53
75 / 63 / 50 / 63
71 / 70 / 71 / 61
64 / 63 / 58 / 46
86 / 66 / 77 / 68
98 / 71 / 53 / 64
103 / 53 / 81 / 49
91 / 81 / 70 / 70

Do this problem in Excel as follows.

Use columns A, B, C, E and F on the Excel spreadsheet for data

In the first row of Columns B, C, D and E put in 0hr, 2hr, 4hr and 6hr. Starting in Cell A2 Put in the letters A through T to identify the employees – unless, of course, you want to suggest some names.

Now put in the data in columns B, C, D and E, skipping column A

If you bring this document into Word, the data can be moved into the Excel worksheet by highlighting the cells you want and copying and pasting.

To fill column F in cell F2 write =B2 after your 'enter' this cell should read '67'

Use the 'edit' pull-down menu and 'copy' cell F2

Use the 'edit' pull-down menu and 'paste' in cells F3 through F21. Now column F will be identical to B except for the heading. This can also be done as a simple copy and paste. Save your data as time1.xls

Use the 'tools' pull-down menu and pick 'data analysis' (If you cannot find this, use Tools and Add-Ins to put in the analysis packs.)

Pick 'ANOVA: Single Factor. Set input range to $B$1:$E$21. Select 'New worksheet ply' and 'columns' , check 'labels in first row' hit 'OK' and save your results as treslt1.xls. In order to check for the effect of the fact that the data is blocked by employees, repeat the analysis using ‘ANOVA: Two-Factor without replication. Set input range to $A$1:$E$21, check ‘labels,’ and save your results as treslt2.xls

Answer the following: Is there a significant difference between the task completion times according to the number of hours worked? How is this conclusion affected by blocking by employees?

252grass4-041 4/02/04

Take the last digit of your student number (if it's zero, use 10). Go back to your original data or use the 'file' pull-down menu to open time1.xls.

To fill column B this time in cell B2 write =F2+x, replacing x with the last digit of your social security number.

Use the 'edit' pull down menu and 'copy' cell B2

Use the 'edit' pull down menu and 'paste' in cells B3 through B21. Now column B will be more than the original B by the amount of your value of x. Save your data as time3.xls.

Run the one-way ANOVA again and save your results as treslt3.xls

Submit the data and results with your Student number. The most effective way to do this is to paste the results into a Word document and then add neat hand or typed notes. Indicate what hypotheses were tested, what the p-value was and whether, using the p-value, you would reject the null if (i) the significance level was 5% and (ii) the significance level was 10%, explaining why. You will have two answers for each of your two problems.

For your lastANOVA do a Scheffe confidence interval and a Tukey-Kramer interval or procedure for each of the possible differences between means and report which are different at the 5% level according to each of the 2 methods. Now on the basis of these data, how would you react to a proposal that employees only be allowed to work for four hours a day at this task? Why?

Extra Credit: Take the data from your last ANOVA and perform a Levene test on it using the third example in 252mvarex. as a pattern for your calculations. Make sure that you explain what is being tested and what you conclude. Hand in separately – this will be treated as extra credit on your next take-home exam.

Extra Extra Credit: Do a Bartlett test using the example in 252mvar as your pattern. It turns out that your ANOVA has just enough columns to do this test.

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