Confused about Corps Supply Quality

Hey there, until today I thought the ASQ of a Corp only depends on the number of different Products used and their Average Quality but not the total number of used Product of each Category. But today I saw different Corps that had a lower ASQ if you calculate with what I said above and still had a higher Quality Output then my Corps, Quality Upgrades are maxed in my and the other Corps and all are of the same Product Type. So, if anyone could tell me where the error is, either in my thoughts or somewhere else, I'd be glad if you could tell

The average is weighted.
If you use 10.000 tons of one product and 1.000 tons of another, the quality of the product you use 10.000 tons of, will weigh heavier on the average that the one you use much less of.

I hope it is clear.

yes, thanks andy

why isnt it possible to specify the quality you want per product used in a corporation? or is it and i just cant find that feature