In: Statistics and Probability
We expect that there is no difference in proportion of status of employment between male and female recent business graduates.
a) insert a frequency table and a bar chart or a pie chart labeled properly. USING EXCEL
b) Perform hypothesis test: Calculate the P-value and make the conclusion (reject or fail to reject Ho). Insert Excel software output.
C)
Calculate the corresponding confidence interval and check if the conclusion is the same
Status | Gender |
Part-time | F |
Part-time | M |
Full-time | M |
Full-time | F |
Part-time | M |
Part-time | M |
Part-time | F |
Full-time | F |
Full-time | F |
Full-time | F |
Full-time | F |
Full-time | F |
Part-time | F |
Full-time | M |
Part-time | F |
Full-time | F |
Full-time | F |
Part-time | M |
Part-time | M |
Part-time | F |
Part-time | F |
Part-time | F |
Full-time | M |
Part-time | F |
Part-time | M |
Part-time | M |
Full-time | M |
Part-time | M |
Full-time | M |
Full-time | F |
Part-time | F |
Part-time | M |
Part-time | M |
Part-time | M |
Full-time | F |
Full-time | M |
Part-time | F |
Part-time | F |
Full-time | F |
Full-time | M |
Full-time | F |
Full-time | F |
Full-time | F |
Part-time | M |
Full-time | M |
Full-time | M |
Part-time | M |
Part-time | M |
Full-time | F |
Part-time | M |
Part-time | F |
Full-time | M |
Part-time | M |
Part-time | M |
Full-time | F |
Part-time | F |
Full-time | M |
Part-time | M |
Part-time | F |
Part-time | M |
Part-time | M |
Part-time | F |
Part-time | F |
Part-time | F |
Part a
The required bar chart for the given data by using excel is given as below:
Part b
b) Perform hypothesis test: Calculate the P-value and make the conclusion (reject or fail to reject Ho). Insert Excel software output.
Solution:
Here, we have to use z test for the difference in population proportions.
H0: p1 = p2 versus H1: p1 ≠ p2
This is a two tailed test.
We assume α = 0.05
The test statistic formula is given as below:
Z = (P1 – P2) / sqrt(P*(1 – P)*((1/N1) + (1/N2)))
Where,
X1 = 11
X2 = 16
N1 = 31
N2 = 33
P = (X1+X2)/(N1+N2) = (11+16) / (31+33) = 0.4219
P1 = X1/N1 = 11/31 = 0.35483871
P2 = X2/N2 = 16/33 = 0.484848485
Z = (0.35483871 – 0.484848485) / sqrt(0.4219*(1 - 0.4219)*((1/31) + (1/33)))
Z = -0.13000978 / 0.123526011
Z = -1.0525
Test statistic = Z = -1.0525
P-value = 0.2926
(by using z-table)
P-value > α = 0.05
So, we do not reject the null hypothesis
There is sufficient evidence to conclude that there is no difference in proportion of status of employment between male and female recent business graduates at α = 0.05 level of significance.
Excel output for above test is given as below:
Z Test for Differences in Two Proportions |
|
Data |
|
Hypothesized Difference |
0 |
Level of Significance |
0.05 |
Group 1 |
|
Number of Items of Interest |
11 |
Sample Size |
31 |
Group 2 |
|
Number of Items of Interest |
16 |
Sample Size |
33 |
Intermediate Calculations |
|
Group 1 Proportion |
0.35483871 |
Group 2 Proportion |
0.484848485 |
Difference in Two Proportions |
-0.13000978 |
Average Proportion |
0.4219 |
Z Test Statistic |
-1.0525 |
Two-Tail Test |
|
Lower Critical Value |
-1.9600 |
Upper Critical Value |
1.9600 |
p-Value |
0.2926 |
Do not reject the null hypothesis |
C) Calculate the corresponding confidence interval and check if the conclusion is the same
Confidence interval for difference between two population proportions:
Confidence interval = (P1 – P2) ± Z*sqrt[(P1*(1 – P1)/N1) + (P2*(1 – P2)/N2)]
Where, P1 and P2 are sample proportions for first and second groups respectively.
Confidence level = 95%
Critical Z value = 1.96
(by using z-table)
Confidence interval = (0.35483871 – 0.484848485) ± 1.96*sqrt[(0.35483871*(1 – 0.35483871)/31) + (0.484848485*(1 – 0.484848485)/33)]
Confidence interval = -0.1300 ± 0.2397
Lower limit = -0.1300 - 0.2397 = -0.3697
Upper limit = -0.1300 + 0.2397 = 0.1097
The required confidence interval by using excel is given as below:
Confidence Interval Estimate |
|
of the Difference Between Two Proportions |
|
Data |
|
Confidence Level |
95% |
Intermediate Calculations |
|
Z Value |
1.9600 |
Std. Error of the Diff. between two Proportions |
0.1223 |
Interval Half Width |
0.2397 |
Confidence Interval |
|
Interval Lower Limit |
-0.3697 |
Interval Upper Limit |
0.1097 |
The 95% confidence interval for the difference in population proportions is given as (-0.3697, 0.1097). The value zero is lies within above confidence interval, so we do not reject the null hypothesis and concluded that there is no difference in proportion of status of employment between male and female recent business graduates.