T-Test 1: Satisfaction Level vs Attrition

Technical Interpretation:

If the p-value < 0.01, we reject the null hypothesis and conclude that the means are significantly different.

Non Technical Interpretation:

People who left the company had much lower satisfaction levels than the ones who stayed. Low job satisfaction increases the likelihood of leaving.

## 
##  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

T-Test 2: Average Monthly Hours vs Attrition

Technical Interpretation:

The small p-value (< 0.02) indicates a statistically significant difference in means.

Non Technical Interpretation:

The employees who left tend to work more hours that the ones who stayed. Working more hours increases the likelihood of someone leaving.

## 
##  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 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

T-Test 3: Last Evaluation Score vs Attrition

Technical Interpretation:

The p-value was (> 0.01) meaning there is no statistically significant difference.

Non Technical Interpretation:

The performance rating did not have anthing to do with who quit. Both High and Low performers are just as likly to leave.

## 
##  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 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

T-Test 4: Time Spent at Company vs Attrition

Technical Interpretation:

The p-value (< 0.01) means the difference is statistically significant.

Non Technical Interpretation:

Employees who leave the company have been there longer on average. Possibly meaning employees burn or or retire here.

## 
##  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 0 and group 1 is not equal to 0
## 95 percent confidence interval:
##  -0.5394767 -0.4534706
## sample estimates:
## mean in group 0 mean in group 1 
##        3.380032        3.876505