3) random pattern. 4) seasonal pattern. Question 15 (2 points) Which one of the following is most useful for measuring the bias in a forecast? 1) Standard deviation of forecast errors 2) Percentage forecast error in period t 3) Cumulative sum of forecast errors 4) Mean absolute deviation of forecast errors Question 16 (3 points) Saved Professor Willis noted that the popularity of his office hours mysteriously rose in the middle and the end of each semester, falling off to virtually no visitors throughout the rest of the year. The demand pattern at work 1) random. O2) seasonal