“Two heads are better than one.” If that’s true, then how good would several heads be? To find out, a statistics instructor drew a line across the chalkboard and asked her class to estimate its length to the nearest inch. She collected their estimates, which ranged from 33 to 61 inches, and calculated the mean value. She reported that the mean was 42.25 inches. She then measured the line and found it to be 41.75 inches long.

Does this show that “several heads are better than one”? What statistical theory supports this occurrence? Explain how.