1. This case is complex because in order to make any improvements many variables have to be taken into account. The design is very complicated becaue it is a cross-functional process. Many people with different expert knowledge worked together on the design so they are all needed to find solutions. The engineers have to divide the variables causing the need for improvement from the other variables that are not at the basic level of the problem. In other words true root causes have to be sorted out and addressed. Thoes root causes are the independent variables called critical X that have an impact on solving the problem. The other variables are the insignificant many.
2. Maybe the Ni-Au made the boards work better so they were used. Maybe the nickel-gold (Ni-Au) boards seemed like they would work better in theory but the designers did not have money in the budget to make a comparative analysis. Time might have been short and the boards were needed right away. The engineering journals may have had articles describing research of the Ni-Au boards that made them seem like the best option.
3. The F stands for a ratio the variance between group means/mean within group variances. The F needs to be positive to be useful. It is a measure of whether or not the test gave good data. The F for vendors is equal to 15.27, and for the finish is 6.87, and for the interaction is 5.85 so the impact of the three things needs to be evaluated for their impact on the Ni-Au board and the problem that wave solder skips. The impacts that need to be evaluated have narrowed down to different vendors, the different finishes available and effects of interactions.
