Question: The general manager of a chain of furniture stores believes that experience is the most important factor in determining the level of success of a salesperson. To examine this belief she records last month's sales (in $1,000s) & the years of experience of 10 randomly selected salespeople. These data are listed below.
Salesperson
|
Years of Experience
|
Sales
|
1
|
0
|
7
|
2
|
2
|
9
|
3
|
10
|
20
|
4
|
3
|
15
|
5
|
8
|
18
|
6
|
5
|
14
|
7
|
12
|
20
|
8
|
7
|
17
|
9
|
20
|
30
|
10
|
15
|
25
|
[A] Interpret the value of the slope of the regression line.
[B] Estimate the standard error of estimate & describe what this statistic tells you about the regression line.
[C] Determine the coefficient of determination & discuss what its value tells you about the two variables.
[D] Calculate the coefficient of correlation. What sign does it have? Why?
[E] Draw a scatter diagram of the data to determine whether a linear model appears to be appropriate.
[F] Using Excel, Run the regression using years of Experience as the independent variable (x) & sales the dependent variable (y).
[G] Determine the least squares regression line.
[H] Predict with 95% confidence the monthly sales of a salesperson with 10 years of experience.
[I] Predict with 95% confidence the average monthly sales of all salespersons with 10 years of experience.
[J] Use the regression equation in the table to determine the predicted values of y.