1) Satisfaction Level vs. Last Evaluation

Correlation

## 
##  Pearson's product-moment correlation
## 
## data:  hr$satisfaction_level and hr$last_evaluation
## t = 12.933, df = 14997, p-value < 2.2e-16
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  0.08916727 0.12082195
## sample estimates:
##       cor 
## 0.1050212

Plot

Technical Interpretation:

  • The correlation is 0.105 there is a perfect positive correlation between average monthly hours and last evaluation score. The p-value (< 2.2e-16) is smaller than my alpha (0.01), so we reject the Ho.

Non-Technical Interpretation:

  • With more average monthly hours, employees last evaluation slightly increases.

2) Number of Projects vs. Time Spent at the Company

Correlation

## 
##  Pearson's product-moment correlation
## 
## data:  hr$time_spend_company and hr$number_project
## t = 24.579, df = 14997, p-value < 2.2e-16
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  0.1813532 0.2121217
## sample estimates:
##       cor 
## 0.1967859

Plot

Technical Interpretation:

  • The p-value is smaller than my alpha (0.01) therefore we reject the null hypothesis (Ho) and conclude that there is a weak and positive correlation between time spent at company and projects.

Non-Technical Interpretation:

  • As time spent at the company goes up, the number of projects goes up slightly.

3) Time Spent at the Company vs. Satisfaction Level

Correlation

## 
##  Pearson's product-moment correlation
## 
## data:  hr$time_spend_company and hr$satisfaction_level
## t = -12.416, df = 14997, p-value < 2.2e-16
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  -0.11668153 -0.08499948
## sample estimates:
##        cor 
## -0.1008661

Plot

Technical Interpretation:

  • The correlation is -0.101, which is a very weak negative relationship between time spent at the company and satisfaction level. The p-value is < 2.2e-16 is smaller than the alpha and the null hypothesis is rejected.

Non-Technical Interpretation:

  • Employees who have been at the company longer have slightly lower satisfaction levels.

4) Average Monthly Hours vs. Last Evaluation

Correlation

## 
##  Pearson's product-moment correlation
## 
## data:  hr$average_montly_hours and hr$last_evaluation
## t = 44.237, df = 14997, p-value < 2.2e-16
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  0.3255078 0.3538218
## sample estimates:
##       cor 
## 0.3397418

Plot

Technical Interpretation:

  • There is a moderate positive relationship between average monthly hours and last evaluation score because the correlation is 0.340.A < 2.2e-16 p-value confirms the Ho is rejected.

Non-Technical Interpretation:

  • Employees who work more hours per month receive slightly higher evaluation scores.