T.test 1
##
## 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
- Reject Ho because P value is small (less than 0.01). Therefore,
there is a difference in average monthly hours between employees that
stayed vs left.
- Techincal term - Employees that worked more hours left.
T.test 2
##
## 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
- We do not reject Ho since 0.4683 > .0.01 and therefore is no
difference of last evaluation score between employees who stayed and
those that left.
- This suggest that last_evaluation scores do not significantly affect
whether an employee leaves or stays.
- Non Technical : Employees who left and those that stayed had similar
performance evaluations which does not determine whether evaluation
score has impact on employee status.
T.test 3
##
## Welch Two Sample t-test
##
## data: hr$number_project by hr$left
## t = -2.1663, df = 4236.5, p-value = 0.03034
## alternative hypothesis: true difference in means between group Stayed and group Left is not equal to 0
## 95 percent confidence interval:
## -0.131136535 -0.006540119
## sample estimates:
## mean in group Stayed mean in group Left
## 3.786664 3.855503
- We do not reject Ho since 0.01 < 0.03, therefore there is no
statistical difference between number of projects and employee
status.
- Non - technical : This suggests that employees with certain amount
of projects doesn’t determine whether an employee leaves or stays.
T.test 4
##
## 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
- We reject Ho because the p-value (2.2e-16) is very small comapred to
0.01, therefore the difference is significant.
- Non-technical : we are confident that employees with more projects
left the company.