Same data, different analysts: variation in effect sizes due to analytical decisions in ecology and evolutionary biology

• Autores: Gould, Elliot; Fraser, Hannah S.; Parker, Timothy H.; Nakagawa, Shinichi; Griffith, Simon C.; Vesk, Peter A.; Fidler, Fiona; Hamilton, Daniel G.; Abbey Lee, Robin N.; Abbott, Jessica K.; Aguirre, Luis A.; Alcaraz, Carles; Aloni, Irith; Altschul, Drew; Arekar, Kunal; Atkins, Jeff W.; Atkinson, Joe; Baker, Christopher M.; Barrett, Meghan; Bell, Kristian; Bello, Suleiman Kehinde; Beltrán, Iván; Berauer, Bernd J.; Bertram, Michael Grant; Palacio, Facundo Xavier; Youngflesh, Casey; Zilio, Giacomo; Zimmer, Cédric; Zimmerman, Gregory Mark; Zitomer, Rachel A.
• Año de publicación: 2025
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: ANALYTICAL HETEROGENEITY; METASCIENCE; MANY-ANALYST; REPLICATION CRISIS; REPRODUCIBILITY
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Although variation in effect sizes and predicted values among studies of similar phenomena is inevitable, such variation far exceeds what might be produced by sampling error alone. One possible explanation for variation among results is differences among researchers in the decisions they make regarding statistical analyses. A growing array of studies has explored this analytical variability in different fields and has found substantial variability among results despite analysts having the same data and research question. Many of these studies have been in the social sciences, but one small “many analyst” study found similar variability in ecology. We expanded the scope of this prior work by implementing a large-scale empirical exploration of the variation in effect sizes and model predictions generated by the analytical decisions of different researchers in ecology and evolutionary biology. We used two unpublished datasets, one from evolutionary ecology (blue tit, Cyanistes caeruleus, to compare sibling number and nestling growth) and one from conservation ecology (Eucalyptus, to compare grass cover and tree seedling recruitment). The project leaders recruited 174 analyst teams, comprising 246 analysts, to investigate the answers to prespecified research questions. Analyses conducted by these teams yielded 141 usable effects (compatible with our meta-analyses and with all necessary information provided) for the blue tit dataset, and 85 usable effects for the Eucalyptus dataset. We found substantial heterogeneity among results for both datasets, although the patterns of variation differed between them. For the blue tit analyses, the average effect was convincingly negative, with less growth for nestlings living with more siblings, but there was near continuous variation in effect size from large negative effects to effects near zero, and even effects crossing the traditional threshold of statistical significance in the opposite direction. In contrast, the average relationship between grass cover and Eucalyptus seedling number was only slightly negative and not convincingly different from zero, and most effects ranged from weakly negative to weakly positive, with about a third of effects crossing the traditional threshold of significance in one direction or the other. However, there were also several striking outliers in the Eucalyptus dataset, with effects far from zero. For both datasets, we found substantial variation in the variable selection and random effects structures among analyses, as well as in the ratings of the analytical methods by peer reviewers, but we found no strong relationship between any of these and deviation from the meta-analytic mean. In other words, analyses with results that were far from the mean were no more or less likely to have dissimilar variable sets, use random effects in their models, or receive poor peer reviews than those analyses that found results that were close to the mean. The existence of substantial variability among analysis outcomes raises important questions about how ecologists and evolutionary biologists should interpret published results, and how they should conduct analyses in the future.
Fil: Gould, Elliot. University of Melbourne; Australia
Fil: Fraser, Hannah S.. University of Melbourne; Australia
Fil: Parker, Timothy H.. Whitman College; Estados Unidos
Fil: Nakagawa, Shinichi. University of New South Wales; Australia
Fil: Griffith, Simon C.. Macquarie University; Australia
Fil: Vesk, Peter A.. University of Melbourne; Australia
Fil: Fidler, Fiona. University of Melbourne; Australia
Fil: Hamilton, Daniel G.. Monash University; Australia
Fil: Abbey Lee, Robin N.. Länsstyrelsen Östergötland; Suecia
Fil: Abbott, Jessica K.. Lund University; Suecia
Fil: Aguirre, Luis A.. University of Massachusetts; Estados Unidos
Fil: Alcaraz, Carles. Institut de Recerca I Tecnologia Agroalimentàries; España
Fil: Aloni, Irith. Ben Gurion University of the Negev; Israel
Fil: Altschul, Drew. The University of Edinburgh; Reino Unido
Fil: Arekar, Kunal. Indian Institute of Science; India
Fil: Atkins, Jeff W.. United States Department Of Agriculture. Horticultural Research Laboratory;
Fil: Atkinson, Joe. University Aarhus; Dinamarca
Fil: Baker, Christopher M.. University of Melbourne; Australia
Fil: Barrett, Meghan. Purdue University; Estados Unidos. Indiana University; Estados Unidos
Fil: Bell, Kristian. Deakin University; Australia
Fil: Bello, Suleiman Kehinde. King Abdulaziz University; Arabia Saudita
Fil: Beltrán, Iván. Macquarie University; Australia
Fil: Berauer, Bernd J.. University of Hohenheim; Alemania
Fil: Bertram, Michael Grant. Sveriges Lantbruksuniversitet (slu);
Fil: Palacio, Facundo Xavier. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Ornitología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina
Fil: Youngflesh, Casey. Michigan State University; Estados Unidos
Fil: Zilio, Giacomo. Université Montpellier II; Francia
Fil: Zimmer, Cédric. Université Sorbonne Paris Nord; Francia
Fil: Zimmerman, Gregory Mark. Lake Superior State University; Estados Unidos
Fil: Zitomer, Rachel A.. University of Oregon; Estados Unidos