Info 5080 Research Methods

INFO 5080 RESEARCH METHODS

INFERENTIAL STATISTICS ASSIGNMENT

The management of ACME Automotive Repair Company, with over 400 franchises nationwide, has become concerned with the percentage of parts being ordered by mechanics and then returned as the wrong part. Since there is a 20% restocking fee for returned parts, the cost of these mistakes is considerable.

Management contracts with Information Solutions, Inc. (with whom you work) to consult on this situation. After on-site interviews and a job analysis, IS, inc. management proposes the following actions:

Randomly select five franchise locations with a total of 20 mechanics.

Provide access for these mechanics to Autoparts.com, an online interactive parts ordering service that allows the mechanic to view the part from many different views as well as to visualize the part installed on the particular make and model selected. (Note, there is a charge for each password assigned, but searching is not time sensitive.)

Provide access to training in the use of Autoparts.com for any of the 20 mechanics who choose to participate.

Collect information on a number of variables (See data sheet.)

Analyze the data to answer the following questions for management:

What is the relationship between attending training and preferred source of ordering parts?
What is the relationship between number of hours using Autoparts.com and number of hours using standard auto parts manual?
Is there a significant difference in the percentage of returned parts between those who prefer Autoparts.com and those who prefer using the standard auto parts manual?
Is there a significant difference in the percentage of returned parts between those who attended training and those who did not?

IS, inc management assigns you the task of analyzing the data and presenting a report to the management of ACME Automotive Repair Company. Analyze the data and prepare a report. Just as you are about to turn in your report, top management at IS, inc. informs you, “ACME mangement reports that some of their mechanics spend a lot of time on Autoparts.com. They want to know if that is okay.” What do you say?

ACME Auto Repair Company

SubjectPreferred SourceAttendedHours UsingHours Using% of

#for ordering partstraining?Autoparts.Standardparts

commanualreturned

1Autoparts.comN7612

2ManualN11926

3Autoparts.comY1458

4Autoparts.comY1239

5ManualN12123

6Autoparts.comY1626

7Autoparts.comY1904

8ManualY31921

9Autoparts.comY17310

10ManualN43620

11Autoparts.comN6912

12ManualN21825

13Autoparts.comY1547

14Autoparts.comY1328

15ManualN0239

16Autoparts.comY1716

17Autoparts.comY1804

18ManualY121213

19Autoparts.comY17411

20ManualN33620

INFO 5080

Inferential Statistical Homework Practice Homework

QUESTION 1

Regarding the question 5A, which of these would be an appropriate Null Hypothesis?

1. / There is a relationship between attending training and the preferred source of auto parts.
2. / There should be a relationship between attending training and the preferred source of auto parts.
3. / There is no relationship between attending training and the preferred source of auto parts.
4. / There will be no difference in the number of auto parts ordered.

QUESTION 2

Based on the observed and expected data (before you calculate the statistic), do you see a relationship?

1. / No, it looks like about the same number of mechanics prefer the two sources of information.
2. / It appears that mechanics who took the training prefer using Autoparts.com and those that did not prefer using the manual. Yes, there does seem to be a relationship.
3. / Yes, it appears that mechanics who attended training prefer the manual and those who did not prefer the Autoparts.com
4. / It appears that those who took the training had a higher percentage of returned parts.

QUESTION 3

What is the correct statistical tool to use for this question?

1. / Chi Square Test of Independence
2. / Chi Square Goodness of Fit
3. / T test for the Pearson's r
4. / Independent t Test

QUESTION 4

We can reject the Null Hypothesis and state that we are at least 95% sure that there is a relationship between attending training and preferred source of ordering parts.

True

False

QUESTION 5

What is the correct statistical tool to address the research question, "Is there a relationship between the number of hours using Autoparts.com and the number of hours using the Standard auto parts manual?" ?

1. / Chi Square Test of Independence
2. / Independent t test
3. / t test for the Pearson's Correlation Coefficient
4. / Chi Square Goodness of Fit

QUESTION 6

The Pearson's r for the relationship between the number of hours using Autoparts.com and the number of hours using the standard auto parts manual is -.81 What does this tell you? READ ALL OF THE CHOICES BEFORE SELECTING ONE!!

1. / The more hours a subject used Autoparts.com, the less they tended to use the standard parts manual.
2. / There is a strong negative relationship between hours spent using Autoparts.com and the hours spent using the standard parts manual.
3. / The more hours a subject used Autoparts.com, the more they tended to use the standard parts manual.
4. / 1 and 2, but not 3.

QUESTION 7

The number of degrees of freedom for this problem is ______.

QUESTION 8

Does this statement correctly address the Null Hypothesis? "Since my obtained t for the test of the Pearson's r is -6.24 and this is NOT greater than the table statistic of 2.10, I do NOT reject the null hypothesis. I am not at least 95% sure that there will be a non-zero relationship in the population."

True

False

QUESTION 9

Which of the following is the best null hypothesis for research question 5C?

1. / There is not a significant difference in the percentage of returned parts between those who prefer using autoparts.com and those who prefer using the standard auto parts manual.
2. / There is not a difference in the percentage of returned parts between those who prefer using autoparts.com and those who prefer using the standard auto parts manual.
3. / There is not a significant relationship between the percentage of parts returned as to those who prefer autoparts.com and those who prefer using the standard parts manual.
4. / The percentage of returned parts does not match the overall percentage of returned parts of the population.

QUESTION 10

Based on observing the data and descriptive statistics, what do you think about the research question? Choose the best answer.

1. / It appears that those who prefer autoparts.com have a much greater percentage of returned parts than those who prefer the manual. Is the difference large enough that I would be at least 95% sure that this difference would be found in the population of mechanics?
2. / It appears that those who prefer autoparts.com have a much smaller percentage of returned parts than those who prefer the manual and that this may be large enough that a difference would be found in the population of mechanics?
3. / The mean % of parts returned (12.6%) for those that prefer autoparts.com is about the same as those that prefer the manual (14.7%), so I don't think that this is significant, i.e., that we will find a difference in the population.
4. / The reseach question is a good one and might well be answered by this research project.

QUESTION 11

What is the best inferential statistic tool to use for this problem?

1. / Because we are comparing the means of two groups, the t test for the Pearson's r should be the tool used.
2. / Chi Square Goodness of Fit
3. / One-way Analysis of Variance
4. / Independent t Test

QUESTION 12

What is the correct Table Statistic for this problem?

1. / 2.88
2. / 2.11
3. / 2.10
4. / .688

QUESTION 13

This one i’m skipping for now.

QUESTION 14

Select which of the following represents the obtained t-test statistic.

1. / 2.10
2. / -3.54
3. / 3.79
4. / 4.53

QUESTION 15

Which of the following is the best concluding statement for this problem?

1. / Since my obtained statistic of -3.79 is less than the table statistic of 2.10, I cannot reject the null hypothesis. I am NOT at least 95% sure that there is a difference in the population in the percentage of returned parts between those who attended training and those who did not.
2. / Since my obtained statistic of -3.79 is less than the table statistic of 2.10, I can reject the null hypothesis. I am at least 95% sure that there is a difference in the population in the percentage of returned parts between those who attended training and those who did not.
3. / Since my obtained statistic of 3.79 (remember to drop the negative sign) is greater than the table statistic of 2.10, I can reject the null hypothesis. I am at least 95% sure that there is a difference in the population in the percentage of returned parts between those who attended training and those who did not.
4. / Since my obtained statistic of 3.79 (remember to drop the negative sign) is greater than the table statistic of 2.10, I can reject the null hypothesis. I am at least 95% sure that there is a relationship in the population in the percentage of returned parts between those who attended training and those who did not.

QUESTION 16

Just as you are about to turn in your report, top management at IS, Inc informs you, "ACME management reports that some of their mechanics spend a lot of time on Autoparts.com" They want to know if that is okay. Select which of the following would be the best answer.

1. / Since the relationship between amount of time spent on Autoparts.com and the percentage of parts returned is negative and significant (We are at least 95% sure that there is a non-zero relationship in the population of mechanics), it is not a problem.
2. / More mechanics prefer using Autoparts.com than the traditional manual.
3. / The relationship between the time spent on Autoparts.com and the percentage of parts returned is negative so that is not good.
4. / The relationship between amount of time spent on Autoparts.com and the perecentage of parts returned is negative but not significant so we are not sure.

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