To test the effect of a new drug twelve patients were examined before the drug was administered and given an initial score (I) depending on the severity of various symptoms. After taking the drug they were examined again and given a final score (F). A decrease in score represented an improvement. The scores for the twelve patients are given in the table below. Score Patient Initial (I) Final (F) 1 61 49 2 23 12 3 8 3. 4 14 4 5 42 28 6 34 27 7 32 20 8 31 20 9 41 34 10 25 15. 11 20 16 12 50 40 Calculate the equation of the line of regression of F on I. On the average what improvement would you expect for a patient whose initial score was 30?