Question

American customer satisfaction index: Starbucks in the U.S. 2006-2016

2006	77
2007	78
2008	77
2009	76
2010	78
2011	80
2012	76
2013	80
2014	76
2015	74
2016	75

1. Plot this set of data as a scatterplot in excel. Insert excel graph here:

2. Find the correlation coefficient.

3. Is it positive or negative?

4. What does the sign tell us?

5.What does the correlation imply about the relationship between the time and the satisfaction?

6. Is the correlation significant? Why or why not? (Answer in 1-2 complete sentences.) (Use the Pearson calculator).

7. Draw the trendline in excel. Can the regression line be used for prediction? No, it is too weak. Insert excel graph here:

Answer 1

1. Plot this set of data as a scatterplot in excel. Insert excel graph here:

Select data and go to insert tab and choose scatter plot

2. Find the correlation coefficient.

r = -0.365 (refer the formula highlighted in yellow)

3. Is it positive or negative?

negative

4. What does the sign tell us?

There would be a negative trend between the variables

5.What does the correlation imply about the relationship between the time and the satisfaction?

There is weak negative linear relationship between time and the satisfaction

. Is the correlation significant? Why or why not?

No the correlation is not significant.

Run a regression analysis in excel followed by below procedures:

1. Go to data tab --> data analysis --> choose Regression

Significance F is nothing but P-value

P-value is 0.27

If the p-value is NOT less than the significance level (α=0.05)

• Decision: DO NOT REJECT the null hypothesis.
• Conclusion: "There is insufficient evidence to conclude that there is a significant linear relationship between x and y because the correlation coefficient is NOT significantly different from zero."

Draw the trendline in excel. Can the regression line be used for prediction? No, it is too weak. Insert excel graph here:

The regression line can be used for prediction