1. Is there a difference in satisfaction level between those that left and those that stayed in the company?

Employees who stayed had a higher satisfaction level than those who left

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

2. Is there a difference in average monthly hours between those that left and those that stayed in the company?

Employees who stayed worked, on average, less hours per month than those who left

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

3. Is there a difference in last evaluation between those that left and those that stayed in the company?

There is no difference in the last evaluation between employees who stayed and employees who left

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