Regression (Textbook Cost)
- The student will calculate and construct the line of best fit between two variables.
- The student will evaluate the relationship between two variables to determine whether that relationship is significant.
Collect the Data Survey 10 textbooks. Collect bivariate data (number of pages in a textbook, the cost of the textbook).
- Complete the table.
Number of Pages Cost of Textbook
- Which variable should be the dependent variable and which should be the independent variable? Why?
- Graph pages vs. cost. Plot the points on the graph in Analyze the Data. Label both axes with words. Scale both axes.
Analyze the Data Enter your data into a calculator or computer. Write the linear equation, rounding to four decimal places.
- Calculate the following:
- a = ______
- b = ______
- correlation = ______
- n = ______
- equation: y = ______
- Is the correlation significant? Why or why not? (Answer in complete sentences.)
- Supply an answer for the following scenarios:
- For a textbook with 400 pages, predict the cost.
- For a textbook with 600 pages, predict the cost.
- Obtain the graph on a calculator or computer. Sketch the regression line.
- Answer each question in complete sentences.
- Does the line seem to fit the data? Why?
- What does the correlation imply about the relationship between the number of pages and the cost?
- Are there any outliers? If so, which point is an outlier?
- Should the outlier, if it exists, be removed? Why or why not?