## Stats Lab

### 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?