Detailed Information on Publication Record
2006
Statistical determination of diagnostic species for site groups of unequal size
TICHÝ, Lubomír and Milan CHYTRÝBasic information
Original name
Statistical determination of diagnostic species for site groups of unequal size
Name in Czech
Statistické stanovení diagnostických druhů pro skupiny lokalit o nestejné velikosti
Authors
TICHÝ, Lubomír (203 Czech Republic) and Milan CHYTRÝ (203 Czech Republic, guarantor)
Edition
Journal of Vegetation Science, Uppsala, Opulus Press, 2006, 110-9233
Other information
Language
English
Type of outcome
Článek v odborném periodiku
Field of Study
10600 1.6 Biological sciences
Country of publisher
Sweden
Confidentiality degree
není předmětem státního či obchodního tajemství
References:
RIV identification code
RIV/00216224:14310/06:00016126
Organization unit
Faculty of Science
UT WoS
000244190100012
Keywords in English
Community classification; Dufrêne-Legendre Indicator Value index; Fidelity; phi coefficient; Presence/absence data; Vegetation database
Tags
Tags
International impact, Reviewed
Změněno: 16/12/2006 19:01, prof. RNDr. Milan Chytrý, Ph.D.
V originále
Aim: Concentration of species occurrences in groups of classified sites can be quantified with statistical measures of fidelity, which can be used for the determination of diagnostic species. However, for most available measures fidelity depends on the number of sites within individual groups. As the classified data sets typically contain site groups of unequal size, such measures do not enable a comparison of numerical fidelity values of species between different site groups. We therefore propose a new method of measuring fidelity with presence/absence data after equalization of the size of the site groups. We compare the properties of this new method with other measures of statistical fidelity, in particular with the Dufrêne-Legendre Indicator Value (IndVal) index. Methods: The size of site groups in the data set is equalized, while relative frequencies of species occurrence within and outside of these groups are kept constant. Then fidelity is calculated using the phi coefficient of association. Results: Fidelity values after equalization are independent of site group size, but their numerical values vary independently of the statistical significance of fidelity. By changing the size of the target site group relative to the size of the entire data set, the fidelity measure can be made more sensitive to either common or rare species. We show that there are two modifications of the IndVal index for presence/absence data, one of which is also independent of the size of site groups. Conclusion: The phi coefficient applied to site groups of equalized size has advantages over other statistical measures of fidelity based on presence/absence data. Its properties are close to an intuitive understanding of fidelity and diagnostic species in vegetation science. Statistical significance can be checked by calculation of another fidelity measure that is a function of statistical significance, or by direct calculation of the probability of observed species concentrations by Fisher s exact test. An advantage of the new method over IndVal is its ability to distinguish between positive and negative fidelity. One can also weight the relative importance of common and rare species by changing the equalized size of the site groups.
In Czech
Byla vypracována metoda pro stanovení diagnostických druhů v a priori daných skupinách lokalit, které se liší svojí velikostí.
Links
| GA206/05/0020, research and development project |
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| MSM0021622416, plan (intention) |
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