Final answer:
To calculate residuals for a scatter plot, you subtract each observed y-value from the corresponding predicted y-value from the regression line. Plot these differences against the x-values to create a residual plot. The regression line is best found using a calculator with a regression function.
Step-by-step explanation:
Calculating Residuals for a Scatter Plot-
To calculate the residuals for a scatter plot, follow these steps:
Subtract each observed y-value from its corresponding predicted y-value to get the residual for each data point. The formula for a residual is ‘observed y - predicted y’.
Plot the residuals on a new graph with the x-values on the horizontal axis and the residuals on the vertical axis. This is your residual plot.
Constructing a Least-Squares Regression Line-
Using a calculator that has a regression function, you can generate the equation of a least-squares regression line, which is then added to your scatter plot. This line represents the predicted y-values based on the independent x-values in the data set. Any data point significantly distant from this line could be considered an outlier.
Once you have the regression line, you can calculate the residuals as outlined in the first step. These residuals are important as they indicate the accuracy of your regression model. A good model will have residuals that are randomly scattered around zero.