Single malt scotches are an acquired taste.  They are distilled from barley at a single distillery and matured in oak casks for at least three years (some for many years).  Scotch cannot be matured in new oak casks because the new oak would overpower the taste of the whiskey, so it is only matured in used scotch.  Clearly the previous use of the cask will impact the taste of the scotch.  The bourbon taste in oak will impact the taste differently than will port or sherry or rum or  maderia.  Similarly, each year that the scotch is in the cask will change the taste since it continues to process.  The water supply will also impact the taste of the final product. 

Single malt scotches tend to be categorized by the region in which they were produced.  While this is useful for those who really know their scotches, it is less useful for the general public .  So, a project called Whisky Classified developed a clustering system to help people understand styles of the common brands.  Said differently, the project helps someone answer the question “if I like this brand, what other brands am I likely to like?”

The developers reviewed tasting notes in recently published books on malt whiskey and from distilleries.  From this, they developed a vocabulary of 500 aromatic and taste descriptors for scotch.  They applied these terms to 86 single malt scotches using a product called ClustanGraphics.  The cluster analysis groups malts into the same cluster when they have broadly the same taste characteristics across all 12 sensory variables.  Technically, the method minimizes the variance within clusters and maximizes the variance between clusters.

The result was ten clusters of single malt whiskies:

Cluster A:   Full-Bodied, Medium-Sweet, Pronounced Sherry with Fruity, Spicy, Malty Notes and Nutty, Smoky Hints

Cluster B:  Medium-Bodied, Medium-Sweet, with Nutty, Malty, Floral, Honey and Fruity Notes

Cluster C: Medium-Bodied, Medium-Sweet, with Fruity, Floral, Honey, Malty Notes and Spicy Hints

Cluster D: Light, Medium-Sweet, Low or No Peat, with Fruity, Floral, Malty Notes and Nutty Hints

Cluster E: Light, Medium-Sweet, Low Peat, with Floral, Malty Notes and Fruity, Spicy, Honey Hints

Cluster F: Medium-Bodied, Medium-Sweet, Low Peat, Malty Notes and Sherry, Honey, Spicy Hints

Cluster G: Medium-Bodied, Sweet, Low Peat and Floral Notes

Cluster H: Medium-Bodied, Medium-Sweet, with Smoky, Fruity, Spicy Notes and Floral, Nutty Hints

Cluster I:  Medium-Light, Dry, with Smoky, Spicy, Honey Notes and Nutty, Floral Hints

Cluster J: Full-Bodied, Dry, Pungent, Peaty and Medicinal, with Spicy, Feinty Notes

Those who want more information about the exercise and especially advice of other scotches they might enjoy should consult Wishart (2006) book.