Similarity measures

83

Q1

89

Q2

90

Steinhaus

91

Kulczynski Quantitative

91

Distance measures

Euclidean

91

Average

92

Chord

92

Geodesic

92

Manhattan

92

Mean character difference

93

Whittaker

93

Canberra

93

Bray Curtis

94

17.1

Simple matching

For measures of similarity between samples based on species presence absence

the observations can be summarised in a simple frequency table:

Sam

Species Present

Sample 2

Species Present

a

Species  Absent

c

where the number of species present in both samples is a, the number of species

present in sample 1 but missing from sample 2 is b, the number of species

missing in sample 1 but present in sample 2 is c and the number of species

missing from both samples is d. The total number of species, N, is therefore

a+b+c+d.

Simple matching is 

(a+d) / N.

Note that this measure gives equal weighting to double zeros and species which

are present in both samples. This is rarely useful in ecological studies.

17.2

Rogers_Tanimoto

For measures of similarity between samples based on species presence absence

the observations can be summarised in a simple frequency table:

Sam

Species Present

Sample 2

Species Present

a

Species  Absent

c

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