The following data were collected by an experimenter using a- composite design:
Assume that a second-degree equation is to be fitted to these data using the method of least squares. (a) What is the matrix of independent variables?
(b) Set up the normal equations that would have to be solved to obtain the least squares estimates b0, b1, b2, b12, b11, and b22·
(c) Solve these norma1 equations.
(d) Criticize the analysis.