In: Statistics and Probability
Question 1. Using the two-sample hypothesis test comparing old call time to new call time at a .05 level of significance, discuss the hypothesis test assumptions and tests used. Provide the test statistic and p-value in your response. Evaluate the results of the hypothesis test with the scenario. Provide recommendations for the vice president.
Question 2. Using new call time and coded quality, develop a prediction equation for new call time. Evaluate the model and discuss the coefficient of determination, significance, and use the prediction equation to predict a call time if there is a defect.
Old Call Time New Call Time Shift Quality Coded Quality
6.5 5.2 AM Y 0 Y= CORRECT
6.5 5.2 AM Y 0 N=INCORRECT
6.5 5.2 AM Y 0
6.5 5.2 AM Y 0
7 5.6 AM Y 0
7 5.6 AM Y 0
7 5.6 AM Y 0
7 5.6 AM N 1
7 5.6 AM Y 0
8 6.4 AM Y 0
8 6.4 AM Y 0
8.5 6.8 AM Y 0
8.5 6.8 AM Y 0
9 7.2 AM Y 0
9 7.2 AM Y 0
9 7.2 AM N 1
9 7.2 AM N 1
9.5 7.6 AM N 1
9.5 7.6 AM Y 0
9.5 7.6 AM Y 0
10 8 AM Y 0
10 8 AM Y 0
10 8 AM Y 0
10 8 AM Y 0
10 8 AM Y 0
10.5 8.4 AM Y 0
10.5 8.4 AM Y 0
10.5 8.4 AM Y 0
10.5 8.4 AM Y 0
10.5 8.4 AM Y 0
10.5 8.4 AM Y 0
10.5 8.4 AM Y 0
10.5 8.4 AM Y 0
11.5 9.2 AM Y 0
11.5 9.2 AM Y 0
11.5 9.2 AM Y 0
12 9.6 AM Y 0
12 9.6 AM Y 0
12 9.6 AM N 1
12 9.6 AM Y 0
12.5 10 AM Y 0
12.5 10 AM N 1
13 10.4 AM Y 0
13 10.4 AM Y 0
13.5 10.8 AM Y 0
15.5 12.4 AM Y 0
16 12.8 AM Y 0
16.5 13.2 AM Y 0
17 13.6 AM Y 0
18 14.4 AM Y 0
6 4.8 PM Y 0
9 7.2 PM N 1
9.5 7.6 PM N 1
10 8 PM Y 0
10.5 8.4 PM Y 0
10.5 8.4 PM Y 0
11 8.8 PM Y 0
11 8.8 PM Y 0
11 8.8 PM Y 0
11 8.8 PM Y 0
11.5 9.2 PM Y 0
11.5 9.2 PM Y 0
11.5 9.2 PM Y 0
12 9.6 PM Y 0
12 9.6 PM Y 0
12 9.6 PM Y 0
12 9.6 PM Y 0
12 9.6 PM Y 0
12 9.6 PM Y 0
12 9.6 PM Y 0
12.5 10 PM Y 0
12.5 10 PM Y 0
12.5 10 PM Y 0
12.5 10 PM Y 0
13 10.4 PM N 1
13 10.4 PM N 1
13.5 10.8 PM Y 0
13.5 10.8 PM Y 0
14 11.2 PM Y 0
14 11.2 PM Y 0
14 11.2 PM Y 0
14 11.2 PM N 1
14 11.2 PM Y 0
14.5 11.6 PM Y 0
14.5 11.6 PM Y 0
14.5 11.6 PM N 1
15 12 PM N 1
15 12 PM Y 0
15.5 12.4 PM N 1
16 12.8 PM Y 0
16.5 13.2 PM Y 0
17 13.6 PM Y 0
17.5 14 PM Y 0
18 14.4 PM Y 0
18 14.4 PM Y 0
18 14.4 PM Y 0
18.5 14.8 PM Y 0
19 15.2 PM Y 0
19.5 15.6 PM Y 0
19.5 15.6 PM Y 0
5.25 4.2 AM Y 0
5.25 4.2 PM Y 0
5.25 4.2 AM Y 0
5.25 4.2 PM Y 0
5.75 4.6 AM Y 0
5.75 4.6 PM Y 0
5.75 4.6 AM Y 0
5.75 4.6 PM Y 0
5.75 4.6 AM Y 0
6.75 5.4 PM Y 0
6.75 5.4 AM Y 0
7.25 5.8 PM Y 0
7.25 5.8 AM Y 0
7.75 6.2 PM Y 0
7.75 6.2 AM Y 0
7.75 6.2 PM N 1
7.75 6.2 AM Y 0
8.25 6.6 PM Y 0
8.25 6.6 AM N 1
8.25 6.6 PM Y 0
8.75 7 AM Y 0
8.75 7 PM Y 0
8.75 7 AM Y 0
8.75 7 PM Y 0
8.75 7 AM Y 0
9.25 7.4 PM Y 0
9.25 7.4 AM Y 0
9.25 7.4 PM Y 0
9.25 7.4 AM Y 0
9.25 7.4 PM Y 0
9.25 7.4 AM Y 0
9.25 7.4 PM Y 0
9.25 7.4 AM Y 0
10.25 8.2 PM Y 0
10.25 8.2 AM Y 0
10.25 8.2 PM Y 0
10.75 8.6 AM Y 0
10.75 8.6 PM Y 0
10.75 8.6 AM Y 0
10.75 8.6 PM Y 0
11.25 9 AM Y 0
11.25 9 PM Y 0
11.75 9.4 AM Y 0
11.75 9.4 PM Y 0
12.25 9.8 AM Y 0
14.25 11.4 PM Y 0
14.75 11.8 AM Y 0
15.25 12.2 PM Y 0
15.75 12.6 AM Y 0
16.75 13.4 PM Y 0
t-Test: Two-Sample Assuming Equal Variances | ||
Variable 1 | Variable 2 | |
Mean | 11.08333 | 8.853333 |
Variance | 11.32103 | 7.327606 |
Observations | 150 | 150 |
Pooled Variance | 9.324318 | |
Hypothesized Mean Difference | 0 | |
df | 298 | |
t Stat | 6.324511 | |
P(T<=t) one-tail | 4.64E-10 | |
t Critical one-tail | 1.649983 | |
P(T<=t) two-tail | 9.28E-10 | |
t Critical two-tail | 1.967957 |
t-Test: Two-Sample Assuming Unequal Variances | ||
Variable 1 | Variable 2 | |
Mean | 11.08333 | 8.853333 |
Variance | 11.32103 | 7.327606 |
Observations | 150 | 150 |
Hypothesized Mean Difference | 0 | |
df | 285 | |
t Stat | 6.324511 | |
P(T<=t) one-tail | 4.9E-10 | |
t Critical one-tail | 1.650218 | |
P(T<=t) two-tail | 9.79E-10 | |
t Critical two-tail | 1.968323 |
From both cases i.e. with equal variances or unequal variances the p-value<0.05, hence we reject the null hypothesis and conclude that there is a significant difference in averages of old call time to new call time.
Q2.
Here new call time is a dependent variable and coded quality is independent variable then the regression equation of new call time on coded quality is
New call time=8.8448+0.0802 Coded quality
The detailed outputs are written below:
SUMMARY OUTPUT | ||||||||
Regression Statistics | ||||||||
Multiple R | 0.009179018 | |||||||
R Square | 8.42544E-05 | |||||||
Adjusted R Square | -0.006671933 | |||||||
Standard Error | 2.715970464 | |||||||
Observations | 150 | |||||||
ANOVA | ||||||||
df | SS | MS | F | Significance F | ||||
Regression | 1 | 0.09199005 | 0.09199 | 0.012471 | 0.911234568 | |||
Residual | 148 | 1091.721343 | 7.376496 | |||||
Total | 149 | 1091.813333 | ||||||
Coefficients | Standard Error | t Stat | P-value | Lower 95% | Upper 95% | Lower 95.0% | Upper 95.0% | |
Intercept | 8.844776119 | 0.234624113 | 37.69764 | 9.08E-78 | 8.381130132 | 9.308422106 | 8.381130132 | 9.308422106 |
X Variable 1 | 0.080223881 | 0.718386697 | 0.111672 | 0.911235 | -1.339396231 | 1.499843992 | -1.339396231 | 1.499843992 |
R-square=0.0084% i.e. 0.0084% of total variation in new call time is explained by the regression equation and it is very poor. Hence for this data, the regression equation is fitted well and this is also seen from the ANOVA table since p-value corresponding to regression is very high i.e. 0.9112>0.05 and the regression coefficient is insignificantly different from zero since its p-value=0.7184>0.05.
Predicted call time if there is a defect=8.8448+0.0802 x1=8.925=8.93