Comparing published cocktail variants does not isolate one ingredient when their proportions or methods also differ.
Optimization legitimately changes multiple variables; document that purpose. A one-variable design can also be limited by uncontrolled serving conditions.
The book's 2:1 Manhattan and 3:1 Black Manhattan change both modifier and relative amount. They can be compared as finished designs, but the comparison alone cannot assign the difference to modifier identity.
Idea
Comparing published cocktail variants does not isolate one ingredient when their proportions or methods also differ.
Why it matters
The book's 2:1 Manhattan and 3:1 Black Manhattan change both modifier and relative amount. They can be compared as finished designs, but the comparison alone cannot assign the difference to modifier identity.
Boundary
Optimization legitimately changes multiple variables; document that purpose. A one-variable design can also be limited by uncontrolled serving conditions.
Evidence and connections
This is Academy synthesis from the source examples, not a tested effect reported by the authors.
Course use
Apply in Lesson 10's recipe-record exercise and the research companion's comparison exercise.
Operation and Applications — evidence connection
Kister's troubleshooting guidance (pp. 48–50 / PDF 61–63) supplies an industrial analogy for distinguishing an observation from a cause and using discriminating tests. This broadens the reasoning connection without treating plant trials as experimental evidence about cocktail preferences.
Chapter review and explicit locators
Existing maturity is retained; industrial mechanisms and sensory applications remain distinct.