Why to use a Decision Matrix?
lFrom the Morphological Chart:
»Generated a large number of solutions
»Assembled “concept variants”
lHow to evaluate these solutions? 
What makes one “better” than another?
lKnowing how to choose between alternatives is an important design activity!
lOne can choose by some arbitrary manner, but it is best to use
a rational approach that can be clearly explained to managers and clients.
lWhat makes a Decision Matrix a rational approach?
»Weighted numerical scores are assigned to various sub-objectives
»Individual scores are summed to give each overall solution choice a numerical score
In groupthink cohesiveness is valued more than good decisions.  Decisions are made based on pressures OTHER THAN evaluating facts and finding the best answer.  Challenger example is taken from the textbook, page 125.
In the Challenger disaster, it was determined that failure of the O-rings due to freezing temperatures caused the explosion.