Consider the following design:

Run A B C D E y 1 −1 −1 −1 1 −1 50 2 1 −1 −1 −1 −1 20 3 −1 1 −1 −1 1 40 4 1 1 −1 1 1 25 5 −1 −1 1 −1 1 45 6 1 −1 1 1 1 30 7 −1 1 1 1 −1 40 8 1 1 1 −1 −1 30

(a) What is the generator for column D?

(b) What is the generator for column E?

(c) If this design were run in two blocks with the AB interaction confounded with blocks, the run d would be in the block where the sign on AB is . Answer either − or +.