Practice Assignment 8 and 9

Part 2:

Null Hypothesis: The average monthly income is equal to $6,200.

Alternative Hypothesis: The average monthly income is not equal to $6,200.

Q2.1 Sample Mean= $5640.232

Q2.2 P-value= 0

Q2.3 Since the p-value is less than 0.05, we reject the null hypothesis.

Conclusion: There is strong statistical evidence that the company’s average monthly income is significantly different from $6,200.

Part 3:

Null Hypothesis: p = 0.12
Alternative Hypothesis: p > 0.12

Q3.1: Sample proportion = 0.171

Q3.2: One-tail p-value = 0

Q3.3:
Since the p-value is less than 0.05, we reject the null hypothesis.

Conclusion: There is sufficient statistical evidence to conclude that the company’s attrition rate is greater than 12%, indicating that the HR director’s concern is justified.

Part 4:

Null Hypothesis: Attrition and Department are independent variables
Alternative Hypothesis: Attrition and Department are dependent variables

Q4.1: The department with the highest raw count of attrition is Research & Development.

Q4.2:
Chi-Square Statistic = 3431.924
Degrees of Freedom (df) = 2
p-value = 0

Q4.3:
Since the p-value is less than 0.05, we reject the null hypothesis.

Conclusion: There is a statistically significant relationship between department and attrition. In other words, the department an employee works in does affect their likelihood of leaving the company.