A manufacturer or soap powder conducted an experiment to investigate the effect of price per box on demand. Each of six different sales regions was assigned a wholesale unit price per box for sale to wholesalers or large supermarket chains in the region. After a one-month period, the percentage y of increase over the preceding month in unit sales per region was calculated. The unit prices assigned to the regions and the percentage increases in sales are shown in the table below: Unit Price Increase in sales (%) 6.40 9.8 6.45 7.6 6.50 6.3 6.55 4.5 6.60 4.2 6.65 2.5 6.70 1.7
a. Which variable is the dependent (response) variable?
b. Which variable is the independent (explanatory) variable? Enter the data (carefully) into an EXCEL worksheet and create a scatterplot of unit price vs increase in sales
c. How would you interpret your scatterplot? Use the Excel DATA/DATA ANALYSIS/REGRESSION tool to run a regression analysis
d. What is the value of the correlation coefficient? How would you interpret this result?
e. What is the value of the coefficient of determination? How would you interpret result?
f. Write the hypotheses for the test of the slope.
g. What is the p-value for the test of the slope? How would you interpret this result?
h. What is the regression formula resulting from this analysis between Unit Price and Increase in Sales?
i. Use the regression formula to estimate the Increase in Sales for a Unit price of 6.90.
j. Use the regression formula to estimate the Increase in Sales for a Unit price of 6.20.