In: Statistics and Probability
A Deloitte employment survey asked a sample of human resource executives how their company planned to change its workforce over the next 12 months. A categorical response variable showed three options: the company plans to hire and add to the number of employees, the company plans no change in the number of employees, or the company plans to lay off and reduce the number of employees. Another categorical variable indicated if the company was private or public. Sample data for 180 companies are summarized as follows.
Employment Plan | Company | |
---|---|---|
Private | Public | |
Add Employees | 37 | 32 |
No Change | 19 | 34 |
Lay Off Employees | 16 | 42 |
Find the value of the test statistic. (Round your answer to three decimal places.)
Find the p-value. (Round your answer to four decimal places.)
p-value =
Solution:
Hypothesis are:
H0: Employment Plan and Company are independent
Vs
H1: Employment Plan and Company are NOT independent
Sample data for 180 companies are summarized as follows.
Employment Plan | Company | |
---|---|---|
Private | Public | |
Add Employees | 37 | 32 |
No Change | 19 | 34 |
Lay Off Employees | 16 | 42 |
Part a) Find the value of the test statistic.
Where
Oij = Observed frequencies for ith row and jth column.
Eij = Expected frequencies for ith row and jth column.
Where
Thus we need to make following table:
Observed Frequencies | |||
Company | |||
Employment Plan | Private | Public | Total |
37 | 32 | 69 | |
Business class | 19 | 34 | 53 |
Economy Class | 16 | 42 | 58 |
Total | 72 | 108 | 180 |
Thus
Thus
Oij | Eij | Oij2/Eij |
---|---|---|
37 | 27.600 | 49.601 |
32 | 41.400 | 24.734 |
19 | 21.200 | 17.028 |
34 | 31.800 | 36.352 |
16 | 23.200 | 11.034 |
42 | 34.800 | 50.690 |
N = 180 |
Thus
Chi-square test statistic =
Part b) Find the p-value
df = ( R - 1) X (C - 1)
R = Number of Rows = 3
C = Number of Columns = 2.
df = ( R - 1) X (C - 1)
df = ( 3 - 1) X (2 - 1)
df = 2 X 1
df = 2
Use following Excel command:
=CHISQ.DIST.RT( x , df)
=CHISQ.DIST.RT(9.440 , 2 )
=0.0089
Thus p-value = 0.0089