End Product Quality

Is this still accurate?

Now, ASQ is reached by the following formula:
[x(PQ_of_x) + y(PQ_of_y) + z(PQ_of_z)]/(x+y+z) = ASQ

From WildEyes guide. The guide itself is dated, trying to mine it for useful data.

So each component that goes into the end product has it's quality multiplied by the number used, and etc.

Clarification:

Is this accurate for all industries. Preliminary reading and results tend to indicate it's off for at least one.

I use this formula in modified form in my corp supply. ( modified to use fewer hand-supplieed products due to large # of corps). It seems to be accurate for all, but I have not analyzed every one. It is a very useful initial tweaking point, tho. Sometimes one supply product is so large in the ratio it makes the others insignificant (sand in a glass corp for example).