TICHÝ, Lubomír and Milan CHYTRÝ. Statistical determination of diagnostic species for site groups of unequal size. Journal of Vegetation Science. Uppsala: Opulus Press, 2006, vol. 17, No 6, p. 809-818. ISSN 110-9233.
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Basic 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
Original language English
Type of outcome Article in a journal
Field of Study 10600 1.6 Biological sciences
Country of publisher Sweden
Confidentiality degree is not subject to a state or trade secret
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 Community classification, Dufrêne-Legendre Indicator Value index, Fidelity, phi coefficient, Presence/absence data, vegetation database
Tags International impact, Reviewed
Changed by Changed by: prof. RNDr. Milan Chytrý, Ph.D., učo 871. Changed: 16/12/2006 19:01.
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.
Abstract (in Czech)
Byla vypracována metoda pro stanovení diagnostických druhů v a priori daných skupinách lokalit, které se liší svojí velikostí.
GA206/05/0020, research and development projectName: Vegetace České republiky: formalizovaná typizace, monografie a expertní systém
Investor: Czech Science Foundation, Vegetation of the Czech Republic: formalized typology, monograph and expert system
MSM0021622416, plan (intention)Name: Diverzita biotických společenstev a populací: kauzální analýza variability v prostoru a čase
Investor: Ministry of Education, Youth and Sports of the CR, Diversity of Biotic Communities and Populations: Causal Analysis of variation in space and time
PrintDisplayed: 1/12/2023 11:09