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

Employees that stayed, on average, are more satisfied.

## 
##  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 0 and group 1 is not equal to 0
## 95 percent confidence interval:
##  0.2171815 0.2362417
## sample estimates:
## mean in group 0 mean in group 1 
##       0.6668096       0.4400980

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

People that left, on average, worked more hours.

## 
##  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?

There is no difference in employees’ last evaluation, between those that left and those that stayed.

## 
##  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