Case 1a
The human resources department was getting reports of retention problems among
information system employees. To study this problem, they gathered data for a sample of
these employees to better understand the issues. They got the following information.
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Starting salaries
On-Road: Percentage of time the employee spent traveling.
State U: Whether the employee graduated from a state university
CIS: Whether the employee graduated from a state university highest degree
is in CIS or a closely related field
Stayed 3 Yrs.: Whether the employee has been with the company for at least
three years
Tenure: The number of months the employees was with the company if they
stayed for less than 3 years
Complete the following analysis. Be sure that graphs, charts are labeled and formatted
properly. See the examples on the web site. You will be asked to submit and present
your analysis and interpretation – to be submitted at the semester. Guidelines for the
format will be posted. Pleased ask if you have questions.
Recommended completion – week 3
A. Use appropriate graph to describe percent with a university degrees
B. Construct stacked box plots of salary by presence of a university degree.
C. Complete a histogram of starting salaries
D. Describe the starting salaries using descriptive measures of center, spread and
relative positions. Be sure to label each measure.
E. Write a paragraph to summarize your observations.
Recommended completion – week 4
F. Construct a 95% confidence interval of starting salaries. Write a statement to
interpret the interval. What are the assumptions?
G. Consider the columns "Stayed 3 year" and “Starting Salaries.”
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Form two groups. Group S1 has the salary for those who stayed less than 3
years and Group S2 has the salary for those who stayed more than 3 years.
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Use an appropriate t-test to compare the mean salary salaries for those who
stay at least 3 years to those who leave before 3 years.
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Construct 95% CI of salaries for those who stay at least 3 years and one for
those who leave before 3 years.
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Construct a 95% CI of the difference in starting salaries for these two
groups.
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What are the test assumptions?
Recommended completion – week 5
H. Sort the data by time on the road.
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Form three groups. Group 1 has less than 40%. Group 2 has form 40% to
60% inclusive. Group 3 has more than 60%
Construct a side-by-side box plot the salaries based on travel requirements.
Note symmetry, spread and center. Compare the salaries of the three groups.
What do they tell you?
Do an Analysis of Variance to compare the salaries of the three groups. Is
there a difference in salaries?
Which group earns the most?
If there is an overall difference do the test to show that the difference is
statistically significant. What are the assumptions for the ANOVA?
Recommended completion – week 6
I. Using salary as the dependent variable and travel requirement as the independent
variable, construct the line of best fit.
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Show the scatter plot.
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What is the equation of the line of best-fit? Interpret the slope.
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What is the Coefficient of determination? Interpret it?
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What is the correlation coefficient? Interpret it.
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Is there a statistically significant relationship between the variables? Do the
appropriate test. Summarize and interpret.