Engineers at the University of Massachusetts studied the viability of using semiconductor

Engineers at the University of Massachusetts studied the viability of using semiconductor lasers for solar lighting in spaceborne applications (Journal of Applied Physics, Sept. 1993). A series of n = 8 experiments with quantum-well lasers yielded the following observations on solar pumping threshold current (y) and waveguide Al mole fraction (x):


a. The researchers theorize that the relationship between threshold current (y) and waveguide Al composition (x) will be represented by a U-shaded curve. Hypothesize a model that corresponds to this theory.

b. Plot the data points in a scattergram. Comment on the researchers’ theory.

c. Fit the quadratic model, E(y) = βo + β1x + β2x2, to the data using the method of least squares.

d. Conduct a formal test of the researchers’ theory. Use α = .10.