Assignment 8

T-Test 1

## 
##  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: The p-value (< 2.2e-16) is less than 0.05, therefore the difference in mean satisfaction level between employees who stayed and those who left is statistically significant.

t-test interpretation: The difference in mean satisfaction level between employees who stayed (0.667) and those who left (0.440) is statistically significant, where the difference is approximately 0.227.

non-technical interpretation: Employees who leave the company are significantly less satisfied than those who stay.

T-Test 2

## 
##  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: The p-value (5.907e-14) is less than 0.05, therefore the difference in mean average monthly hours between employees who stayed and those who left is statistically significant.

t-test interpretation: The difference in mean monthly hours between employees who stayed (199.06) and those who left (207.42) is statistically significant, where the difference is approximately 8.36 hours.

non-technical interpretation: Employees who leave the company tend to work significantly more hours than those who stay.

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 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

p-value interpretation: The p-value (0.03034) is less than 0.05, therefore the difference in mean number of projects between employees who stayed and those who left is statistically significant.

t-test interpretation: The difference in mean number of projects between employees who stayed (3.79) and those who left (3.86) is statistically significant, where the difference is approximately 0.07 projects.

non-technical interpretation: Employees who leave the company tend to handle slightly more projects than those who stay.

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 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: The p-value (< 2.2e-16) is less than 0.05, therefore the difference in mean time spent at the company between employees who stayed and those who left is statistically significant.

t-test interpretation: The difference in mean time spent at the company between employees who stayed (3.38 years) and those who left (3.88 years) is statistically significant, where the difference is approximately 0.50 years.

non-technical interpretation: Employees who leave the company tend to have been at the company longer than those who stay.