1. T-test of Average Monthly Hours by Left

## 
##  Welch Two Sample t-test
## 
## data:  hr$average_montly_hours by hr$left
## t = -7.5323, df = 4875.1, p-value = 5.907e-14
## alternative hypothesis: true difference in means between group Stayed and group Left is not equal to 0
## 95 percent confidence interval:
##  -10.534631  -6.183384
## sample estimates:
## mean in group Stayed   mean in group Left 
##             199.0602             207.4192

p-value: The p-value is very small, thus the difference between means of average monthly hours by left is significant.

Technical Interpretation: We reject the Ho, p-value < 0.01, where the average monthly hours working for employees that left is greater.

Non-Technical Interpretation: Employees that work more hours are more likely to leave.

Graph

2. T-test of Satisfaction Level by Left

## 
##  Welch Two Sample t-test
## 
## data:  hr$satisfaction_level by hr$left
## t = 46.636, df = 5167, p-value < 2.2e-16
## alternative hypothesis: true difference in means between group Stayed and group Left is not equal to 0
## 95 percent confidence interval:
##  0.2171815 0.2362417
## sample estimates:
## mean in group Stayed   mean in group Left 
##            0.6668096            0.4400980

p-value: The p-value is very small, thus the difference between means of satisfaction levels by left is significant.

Technical Interpretation: We reject the Ho, p-value < 0.01, where the satisfaction level for employees that stayed is greater.

Non-Technical Interpretation: Employees that are more satisfied are more likely to stay.

Graph

3. T-test of Evaluation Scores by Left

## 
##  Welch Two Sample t-test
## 
## data:  hr$last_evaluation by hr$left
## t = -0.72534, df = 5154.9, p-value = 0.4683
## alternative hypothesis: true difference in means between group Stayed and group Left is not equal to 0
## 95 percent confidence interval:
##  -0.009772224  0.004493874
## sample estimates:
## mean in group Stayed   mean in group Left 
##            0.7154734            0.7181126

p-value: The p-value is larger than 0.01, thus the difference between means of evaluation scores by left is not significant.

Technical Interpretation: We do not reject the Ho because p-value > 0.01, where the evaluation scores for employees that left or stayed are similar.

Non-Technical Interpretation: There is no difference in the average of evaluation scores for employees who left or stayed.

Graph

4. T-test of Time Spent at the Company by Left

## 
##  Welch Two Sample t-test
## 
## data:  hr$time_spend_company by hr$left
## t = -22.631, df = 9625.6, p-value < 2.2e-16
## alternative hypothesis: true difference in means between group Stayed and group Left is not equal to 0
## 95 percent confidence interval:
##  -0.5394767 -0.4534706
## sample estimates:
## mean in group Stayed   mean in group Left 
##             3.380032             3.876505

p-value: The p-value is very small, thus the difference between means of time spent at the company by left is significant.

Technical Interpretation: We reject the Ho, p-value < 0.01, where the employees who spent more time at the company and left are slightly greater.

Non-Technical Interpretation: Employees that spent more time at the company are slightly likely to leave.

Graph