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Exercise 3662. Points 1, theme: Similarity and Distance

Open exercise
Calculate Dice-Sørensen quotient of similarity between two forest stands where the coverage of tree species is as follows:
Stand 1: Alnus 32% Betula 5%, Picea 17%, Pinus 33%;
Stand 2: Pinus 32%, Picea 22%, Alnus 32%.


You can find the formula for Dice-Sørenseni similarity in Wikipedia. The common share in case of abundance estimates is the minimum of values of the same category in two samples. Excel function MIN() can be used for calculating minimum values (see the attached figure).
Notice that the species in two samples are not listed in the same order. As there is no Betula mentioned in the second stand, its coverage is zero.
Similarity measures can also be calculated using the SDC .
Notice that
  • The SDC does not allow empty cells
  • The observations must be in rows and features in columns
  • The first column must contain case name.
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