Vertical vs. horizontal tasting
The standard
The controlled comparison axis holds everything constant but one variable: in the vertical the wine, in the horizontal the vintage. Only so can the observed difference be ascribed to that one variable.
Criteria
- Exactly one variable changes, all others stay equal
- Vertical means: one wine, many vintages
- Horizontal means: one vintage, many wines
- The tasting conditions are equal for all samples
Distinction
Vertical ≠ horizontal: one axis holds the wine fixed, the other the vintage. The controlled comparison axis determines which question a tasting can answer at all.