Similarity indices I: what do they measure.

Technical Report · Mon Nov 01 00:00:00 EST 1976

DOI:https://doi.org/10.2172/7256702· OSTI ID:7256702

Johnston, J W

A method for estimating the effects of environmental effusions on ecosystems is described. The characteristics of 25 similarity indices used in studies of ecological communities were investigated. The type of data structure, to which these indices are frequently applied, was described as consisting of vectors of measurements on attributes (species) observed in a set of samples. A general similarity index was characterized as the result of a two-step process defined on a pair of vectors. In the first step an attribute similarity score is obtained for each attribute by comparing the attribute values observed in the pair of vectors. The result is a vector of attribute similarity scores. These are combined in the second step to arrive at the similarity index. The operation in the first step was characterized as a function, g, defined on pairs of attribute values. The second operation was characterized as a function, F, defined on the vector of attribute similarity scores from the first step. Usually, F was a simple sum or weighted sum of the attribute similarity scores. It is concluded that similarity indices should not be used as the test statistic to discriminate between two ecological communities.

• Research Organization: Battelle Pacific Northwest Labs., Richland, WA (United States)
• DOE Contract Number: EY-76-C-06-1830
• OSTI ID: 7256702
• Report Number(s): BNWL-2152(Add.1); TRN: 77-012051
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CHEMICAL EFFLUENTS
ENVIRONMENTAL TRANSPORT
BIOLOGICAL EFFECTS
ECOSYSTEMS
INVERTEBRATES
PLANTS
SAMPLING
STATISTICS
VARIATIONS
ANIMALS
BIOMASS
ENERGY SOURCES
MASS TRANSFER
MATHEMATICS
RENEWABLE ENERGY SOURCES
500200* - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)
520200 - Environment
Aquatic- Chemicals Monitoring & Transport- (-1989)