1. T.test between Satisfaction Level and Whether Employee Left the Company or not

## 
##  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

P-value interpretation: Since the P-value is < .05, then there is a significant difference in satisfaction levels between employees who stayed versus who left.

t-test interpretation: The difference in mean Satisfaction Level between leaving the company and staying is significant, where the difference in Satisfaction Level is at least 0.2.

non-technical interpretation: Those who left the company are less satisfied.

2. T.test between Last Evaluation Whether Employee Left the Company or not

## 
##  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

P-value interpretation: Since P-value is > .05, then there is no significant difference between last evaluation and whether the employee left or stayed at the company.

t-test interpretation: The difference in mean Last Evaluation between leaving or staying at the company is not significant, with essentially no difference.

non-technical interpretation: Employees who left versus who stayed at the company did not have a difference in their Last Evaluation score.

3. T.test between Average Monthly Hours and Whether Employee Left the Company or not

## 
##  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

P-value interpretation: Since P-value is < .05, then there is a significant difference between Average Monthly Hours and whether the employee left or stayed at the company.

t-test interpretation: The difference in mean Avg Monthly Hours between leaving or staying at the company is significant, with at least 6.2 monthly hours.

non-technical interpretation: Employees who left versus who stayed at the company did have a difference in their Average Monthly Hours. Employees who left tended to have more hours.

4. T.test between Number of Projects and Whether Employee Left the Company or not

## 
##  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

P-value interpretation: Since P-value is < .05, then there is a significant difference between Time Spent at Company and whether the employee left or stayed at the company.

t-test interpretation: The difference in mean Time Spent at Company between leaving or staying at the company is significant, with at least 0.45 of a year.

non-technical interpretation: Employees who left versus who stayed at the company did have a difference in their Time Spent at the Company. Employees who left tended to have spent a longer time.