Question

The figure displays computer output for data on the amount spent by 50 grocery shoppers. Which are the correct pair of lower and upper cutoffs for identifying outliers?

Answer 1

The cutoffs for outliers are found using two times the standard deviation from the regression line, which would be 32.8 units above or below the line on a TI-83, 83+, or 84+ graphing calculator's scatter plot.

Step-by-step explanation:

To identify outliers in a set of data on a TI-83, 83+, or 84+ graphing calculator, you can use a graphical method involving a scatter plot and lines representing the regression line and those that are two standard deviations above and below this line, labeled as Y2 and Y3. The upper and lower cutoffs for outliers are the values beyond which the residuals are greater than two times the standard deviation (2s) from the regression line. Since the standard deviation (s) mentioned in the data is 16.4, the cutoffs for outliers would be calculated as follows: the lower cutoff is the regression line value minus 2s (which equals 32.8), and the upper cutoff is the regression line value plus 2s (also equals 32.8).