Researchers develop a new method to deal with the deep prejudices of science, starting with birds

The fame of female bird song is growing worldwide, in part thanks to an important article by Karan Odom, Ph.D. 16, Biological Sciences, but it is still understood as a trait found mainly in tropical birds. Evangeline Rose, currently a student PhD student in the same laboratory and first author on a new paper Animal behavior, wanted to watch the song in a temperate species.

During Rose's fieldwork, "I discovered that women were singing, for me, what sounded like men's songs," she says. "So we started thinking about equality, equivalence and how to test it." On the advice of her adviser, Kevin Omland, professor of biological sciences, she contacted Thomas Mathew, a professor of statistics who has expertise in statistical equivalence.

Challenge a paradigm

Working together, the team has modified a statistical method used in generic drug testing to address its needs in ecology and animal behavior behavior. The existing test determines whether generic and brand-name drugs are "statistically equivalent," meaning that they are similar enough to be safely prescribed for the same purpose. The new amendment will allow scientists from other fields to test equivalence. Previously, researchers could only point out that they had not found any significant difference – a very different statement of the fact that two things are perfectly equivalent.

"We really hope this new method will solve some of the issues related to the type of data being published," Rose said. "What's important to be a good scientist is to be unbiased, and the whole tradition of verifying difference really leads to incredible biases among scientists," Omland said. He adds, "There is a whole world of things in nature that we find interesting and important because of their similarity."

For example, in addition to the similarities of songs between the sexes in birds, researchers could use the new test to ask if two species use the same type of habitat, react the same way to predators or consume the same sources of food. Answers to these questions could fill gaps in knowledge or even inform conservation efforts.

"This test is really applicable," says Rose, "and we hope to introduce it further in the field of ecology and evolution."

A new approach

One of the advantages of the new method is that it allows for taking into account unequal sample sizes. In a medical study, researchers can carefully control the size of treatment and control groups. In other fields, from ecology to engineering, to agriculture, this is often not possible. The new test also allows researchers to determine the equivalence of several characters simultaneously, explains Mathew. For example, in this study, the authors found that male and female bird songs were statistically equivalent for five different characteristics, such as the duration of each song and the range of heights produced by the birds.

Rather than checking if two things are exactly the same, the team was looking for a way to determine if two things were "close enough", given a defined margin of difference. Because of this extra layer, "there are additional challenges here," says Mathew.

"Even though this methodology already exists, it has not been applied – even in statistics – with this type of data.This is why I was very enthusiastic when they introduced me to it. this project, "said Mathew. Rose added, "It has been a very good partnership to look at these previously unanswered questions for the female song, and we have also changed this test in a really new and fun way."

Science in mutation

As research on similarities develops, there is also a growing desire to remove bias against the publication of studies finding no significant difference, often referred to as a "negative outcome". This document "is part of an incredible drum beat that is building in the scientific community," Omland said. "The scientific method is increasingly recognized and the test we developed can at least play a small role, and I hope an important role in solving this problem."

Rose, who is considering re-examining the role of Bluebird songs, says she will be bringing these new techniques with her throughout her research career. "I think that in the future, I will reflect on how equivalence can change the questions we ask, and I will always keep in mind that we have additional tools in the toolbox."

Explore further:
Scientists remind their peers: females also sing

More information:
Evangeline M. Rose et al, A new statistical method to test equivalence: an application to the male and female song of bluebirds Animal behavior (2018). DOI: 10.1016 / j.anbehav.2018.09.004