1. T-test: satisfaction level vs left

## 
##  Welch Two Sample t-test
## 
## data:  satisfaction_level by 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

P-value interpretation:

The p-value is very small, therefore the difference between means of mpg by am is significant.

T-test interpretation:

The difference in mean MPG between manual and automatic cars is significant, where the difference in MPG is at least 3.2 MPG.

Non-technical interpretation:

Manual cars are more fuel efficiency

2. T-test: Average Monthly Hours by Attrition (left)

## 
##  Welch Two Sample t-test
## 
## data:  average_montly_hours by left
## t = -7.5323, df = 4875.1, p-value = 5.907e-14
## alternative hypothesis: true difference in means between group 0 and group 1 is not equal to 0
## 95 percent confidence interval:
##  -10.534631  -6.183384
## sample estimates:
## mean in group 0 mean in group 1 
##        199.0602        207.4192

Technical Interpretation

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

Non-Technical Interpretation

Employees with lower satisfaction levels are more likely to leave.

3. T-test: last evaluation score by attrition (left)

## 
##  Welch Two Sample t-test
## 
## data:  last_evaluation by left
## t = -0.72534, df = 5154.9, p-value = 0.4683
## alternative hypothesis: true difference in means between group 0 and group 1 is not equal to 0
## 95 percent confidence interval:
##  -0.009772224  0.004493874
## sample estimates:
## mean in group 0 mean in group 1 
##       0.7154734       0.7181126

Technical interpretation:

The p-value is 0.468275, showing the significance of the difference in last evaluation scores

Non-technical interpretation:

Employees who left generally have higher evaluation scores than those who stayed

4. T-test: number of projects by attrition (left)

## 
##  Welch Two Sample t-test
## 
## data:  number_project by left
## t = -2.1663, df = 4236.5, p-value = 0.03034
## alternative hypothesis: true difference in means between group 0 and group 1 is not equal to 0
## 95 percent confidence interval:
##  -0.131136535 -0.006540119
## sample estimates:
## mean in group 0 mean in group 1 
##        3.786664        3.855503

Technical interpretation:

The p-value is 0.0303407, indicating the significance of the difference in the number of projects between the two groups

Non-technical interpretation:

Employees who left the company were generally involved in more projects than those who stayed