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  • 1 Institute of Ecology and Botany, Alkotmány u. 2-4, Vácrátót, Hungary
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In community ecology, randomization tests with problem specific test statistics (e.g., nestedness, functional diversity, etc.) are often applied. Researchers in such studies may want not only to detect the significant departure from randomness, but also to measure the effect size (i.e., the magnitude of this departure). Measuring the effect size is necessary, for instance, when the roles of different assembly forces (e.g., environmental filtering, competition) are compared among sites. The standard method is to calculate standardized effect size (SES), i.e., to compute the departure from the mean of random communities divided by their standard deviations. Standardized effect size is a useful measure if the test statistic (e.g., nestedness index, phylogenetic or functional diversity) in the random communities follows a symmetric distribution. In this paper, I would like to call attention to the fact that SES may give us misleading information if the distribution is asymmetric (skewed). For symmetric distribution median and mean values are equal (i.e., SES = 0 indicates p = 0.5). However, this condition does not hold for skewed distributions. For symmetric distributions departure from the mean shows the extremity of the value, regardless of the sign of departure, while in asymmetric distributions the same deviation can be highly probable and extremely improbable, depending on its sign. To avoid these problems, I recommend checking symmetry of null-distribution before calculating the SES value. If the distribution is skewed, I recommend either log-transformation of the test statistic, or using probit-transformed p-value as effect size measure.

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Senior editors

Editor(s)-in-Chief: Podani, János

Editor(s)-in-Chief: Jordán, Ferenc

Honorary Editor(s): Orlóci, László

Editorial Board

  • Madhur Anand, CAN (forest ecology, computational ecology, and ecological complexity)
  • S. Bagella, ITA (temporal dynamics, including succession, community level patterns of species richness and diversity, experimental studies of plant, animal and microbial communities, plant communities of the Mediterranean)
  • P. Batáry, HUN (landscape ecology, agroecology, ecosystem services)
  • P. A. V. Borges, PRT (community level patterns of species richness and diversity, sampling in theory and practice)
  • A. Davis, GER (supervised learning, multitrophic interactions, food webs, multivariate analysis, ecological statistics, experimental design, fractals, parasitoids, species diversity, community assembly, ticks, biodiversity, climate change, biological networks, cranes, olfactometry, evolution)
  • Z. Elek, HUN (insect ecology, invertebrate conservation, population dynamics, especially of long-term field studies, insect sampling)
  • T. Kalapos, HUN (community level plant ecophysiology, grassland ecology, vegetation-soil relationship)
  • G. M. Kovács, HUN (microbial ecology, plant-fungus interactions, mycorrhizas)
  • W. C. Liu,TWN (community-based ecological theory and modelling issues, temporal dynamics, including succession, trophic interactions, competition, species response to the environment)
  • L. Mucina, AUS (vegetation survey, syntaxonomy, evolutionary community ecology, assembly rules, global vegetation patterns, mediterranean ecology)
  • P. Ódor, HUN (plant communities, bryophyte ecology, numerical methods)
  • F. Rigal, FRA (island biogeography, macroecology, functional diversity, arthropod ecology)
  • D. Rocchini, ITA (biodiversity, multiple scales, spatial scales, species distribution, spatial ecology, remote sensing, ecological informatics, computational ecology)
  • F. Samu, HUN (landscape ecology, biological control, generalist predators, spiders, arthropods, conservation biology, sampling methods)
  • U. Scharler, ZAF (ecological networks, food webs, estuaries, marine, mangroves, stoichiometry, temperate, subtropical)
  • D. Schmera, HUN (aquatic communities, functional diversity, ecological theory)
  • M. Scotti, GER (community-based ecological theory and modelling issues, trophic interactions, competition, species response to the environment, ecological networks)
  • B. Tóthmérész, HUN (biodiversity, soil zoology, spatial models, macroecology, ecological modeling)
  • S. Wollrab, GER (aquatic ecology, food web dynamics, plankton ecology, predator-prey interactions)

 

Advisory Board

  • S. Bartha, HUN
  • S.L. Collins, USA
  • T. Czárán, HUN
  • E. Feoli, ITA
  • N. Kenkel, CAN
  • J. Lepš, CZE
  • S. Mazzoleni, ITA
  • Cs. Moskát, HUN
  • B. Oborny, HUN
  • M.W. Palmer, USA
  • G.P. Patil, USA
  • V. de Patta Pillar, BRA
  • C. Ricotta, ITA
  • Á. Szentesi, HUN

PODANI, JÁNOS
E-mail: podani@ludens.elte.hu


JORDÁN, FERENC
E-mail: jordan.ferenc@gmail.com

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Community Ecology
Language English
Size A4
Year of
Foundation
2000
Volumes
per Year
1
Issues
per Year
2
Founder Akadémiai Kiadó
Founder's
Address
H-1117 Budapest, Hungary 1516 Budapest, PO Box 245
Publisher Akadémiai Kiadó
Springer Nature Switzerland AG
Publisher's
Address
H-1117 Budapest, Hungary 1516 Budapest, PO Box 245.
CH-6330 Cham, Switzerland Gewerbestrasse 11.
Responsible
Publisher
Chief Executive Officer, Akadémiai Kiadó
ISSN 1585-8553 (Print)
ISSN 1588-2756 (Online)