Problem 5

In a processing plant, it is known that the quality of finished product is a function of the temperature and pressure at which the chemical reactions take place.

It is to model the quality, Y, of a product as a function of temperature, x1 (oF), and the pressure x2 (psi) at which it is produced.

Five inspectors independently assign a quality score (%) to each sample and the quality, Y, is evaluated by averaging the five (5) scores. The resultant data is given in the data table below.

Tasks :

1) Specify algebraically the complete second order model for the data.

2) Use JMP to determine the best model.

3) Produce two bivariate plots: Product quality versus temperature (x1) and product quality versus pressure (x2). Describe the shape of each graph and comment on what this indicates about the adequacy of the possible linear model

Y = b + b1 x1+ b2 x2 + E .

4) From the model obtained in 2), what temperature and/or pressure would you recommend?