1. t-test of Average Monthly Hours by Left

t-test

## 
##  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

Technical Interpretation

We reject the Ho, p-value < 0.01, where the average monthly hours 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

t-test

## 
##  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

Technical Interpretation

We reject the Ho, p-value < 0.01, where the satisfaction level for employees that left is greater

Non-Technical Interpretation

Employees that are less satisfied are more likely to leave

Graph

3. t-test of Time Spent at Company by Left

t-test

## 
##  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

Technical Interpretation

We reject the Ho, p-value < 0.01, where the time spent at the company for employees that left is greater

Non-Technical Interpretation

Employees who’ve been with the company longer are more likely to leave — possibly due to burnout, stagnation, or lack of promotion.

Graph

4. t-test of Last Evaluation by Left

t-test

## 
##  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

Technical Interpretation

We fail to reject the null hypothesis since the p-value is 0.4683, which is much greater than 0.01. This means there is no statistically significant difference in last evaluation scores between employees who left and those who stayed

Non-Technical Interpretation

Performance evaluations do not appear to influence whether an employee leaves the company. In other words, high- or low-performing employees are equally likely to stay or leave

Graph