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Media type:
E-Article
Title:
A MINTAVÉTEL HATÁSA. AZ INTERSPECIFIKUS ASSZOCIÁCIÓ MÉRÉSÉBEN. ELŐZETES MEGJEGYZÉSEK
Contributor:
HAHN, István
imprint:
The Department of Plant Taxonomy and Ecology, L. Eötvös University, 1984
Published in:Abstracta Botanica
Language:
Hungarian
ISSN:
0133-6215
Origination:
Footnote:
Description:
<p>The basic strategy of some divisive clustering techniques is the calculation of the similarity between species. . Several measures are known for this purpose. The simplest method is based on 2×2 contingency tables referring to binary data. The actual values in the cells of this table are influenced by many factors, such as the size of sampling unit. The author's aim is to study the relationship between the conditions and the results of technical sampling in simulated and actual situations. Two fundamental types of similarity coefficients may be distinguished according to their behavior in a spatial process related to plot size. The value of Type I. indices, for example, the Jaccard and Sørensen index, monotonically increases over plot size. These functions do not consider the number of "negative" matches (d) in the contingency table. The Type II. indices (simple matching coefficient, Rogers-Tanimoto formula, etc.) are not monotonous, at a certain plot size a minimum value is taken, then the similarity starts to increase. These functions included in the nominator. The chi-square statistic is quite different from these indices in its response. to plot size changes. Detailed simulation experiments will be carried out to get a deeper insight into the problem of plot size/resemblance relationships.</p>