Consider Exercise 15.6. Use a +1 and –1 scaling for “high”

and “low,” respectively, and do a multiple linear regression with the model with x = reactant concentration (–1, +1) and x = feed rate (–1,

+1).

1. Compute regression coefficients.

2. How do the coefficients b , b , and b relate to the effects you found in Exercise 15.6(a)?

3. In your regression analysis, do t-tests on b , b , and b . How do these test results relate to those in Exercise 15.6

(b) and

(c)?