1. 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

Techinal intpretation

We reject the null h0, p-value < 0.01, where the satisfaction level for employees that left is smaller.

Non techinal intreptation

Employees that stay are more satisified compared to those who left.

Graph

2. 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

Techinal intpretation

We reject the null h0, p-value < 0.01, where the time spent at company for employees that left is greater

Non techinal intreptation

Employees that left spent a longer time at the company

Graph

3. T-test of last evaluation score 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

Techinal intpretation

We reject the null h0, p-value < 0.01, suggesting a significant difference in last evaluation scores between employees who left and those who stayed. On average, employees who left had higher evaluation scores.

Non techinal intreptation

Employees who left had slightly higher evaluation scores on average.

Graph

4. 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

Techinal intpretation

We reject the null h0, p-value < 0.01, indicating that employees who left worked significantly more hours per month than those who stayed.

Non techinal intreptation

Employees who left had slightly higher evaluation scores on average.

Graph