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# Regression analysis

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a. Develop a scatter plot of the data with the dependent variable, cost, on the vertical axis and the independent variable, weight, on the horizontal axis. Does there appear to be a relationship between the two variables? Is the relationship linear?
b. Compute the sample correlation coefficient between the two variables. Conduct a test, using a significance level of 0.05, to determine whether the population correlation coefficient is significantly different from zero.
c. Using a simple linear regression equation to predict the cost of shipping various items. Would you recommend it use a second-order polynomial model instead? Is the second-order polynomial model a significant improvement on the simple linear regression equation?
d. A decision was made to stop shipping products if the shipping charges exceed \$100. The company has asked you to determine the maximum weight for future shipments. Do this for both the first - and second-order models you have developed.