MATH 214 Probability and Statistics for Business
MATH 214 Probability and Statistics for Business
Dr. Ed Donley
Computer Assignment 2
Section 004: Due Wednesday, March 14, 2001
Section 007: Due Thursday, February 15, 2001
Numerous studies have found a causal relationship between an employee’s commitment to the firm and his or her tendency to leave the firm voluntarily. A study published in 1993 [Jaros, S. J., et.al., “Effects of continuance, affective, and moral commitment on the withdrawal process: An evaluation of eight structural equation models”, Academy of Management Journal, Vol. 36, No. 5, Oct. 1993, pp. 951-995.], surveyed 270 employees of in the repair and overhaul group of an aerospace company in the southeast United States. The survey results are at
http://www.ma.iup.edu/~hedonley/ma214/commit.xls
The variables measured are:
Column / Variable / Description1 / Age / Age of the employee in years
2 / Gender / 1 = male, 0 = female
3 / Organizational tenure / Months with organization
4 / Job tenure / Months in current job
5 / Continuance commitment / Measure of the degree to which past behaviors force the employee to be committed to the firm (3 to 21 point scale)
6 / Affective commitment / Measure of the degree to which emotional ties commit the employee to the firm (14 to 98 point scale)
7 / Moral commitment / Measure of the degree to which duty commits the employee to the firm (4 to 28 point scale)
8 / Thinking of quitting / Measure of how often the employee thinks about quitting (1 to 5 point scale)
9 / Search / Measure of how likely the employee is to search for a new job (1 to 5 point scale)
10 / Intent to leave / Measure of the employee’s intentions to leave the firm (2 to 11 point scale)
11 / Leave / 1 = employee quit the firm before the study was over (leavers), 0 = employee stayed with the firm until the end of the study (stayers)
Assume that the 270 employees represent a random sample from the population of employees of all U.S. aerospace companies.
A.Explain why column 11, Leave, is a binomial random variable.
B.Suppose someone claims that the proportion of “leavers” at all U.S. aerospace companies is p = 0.10. Find the expected value and standard deviation for the number of leavers in a random sample of 270 employees from all U.S. aerospace companies.
C.Use Excel to construct a probability distribution for the number of leavers in a sample of 270 employees from all U.S. aerospace companies, assuming that p = 0.10. Plot this distribution using Excel. [Hint: Create the distribution by entering all of the possible values of x in one column. Then enter the formula for the binomial probability in the first row of another column (Insert-> Function-> Statistical-> BINOMDIST). Copy this formula into the other rows of that column. Then use the Chart Wizard to plot the column of probabilities.]
D.Use Excel to find the number of leavers in the sample of 270 employees. (Use Tools-> Data Analysis-> Descriptive Statistics). Compare this with what you found in parts B and C. Does this sample support the claim in part B?