Department of Ecology and Evolutionary Biology, University of California, 130 McAllister Way , Santa Cruz, CA 95060, USA.
Department of Zoology and Physiology, University of Wyoming, 1000 East University Avenue , Laramie, WY 82071, USA.
Proc Biol Sci. 2024 Oct;291(2032):20241640. doi: 10.1098/rspb.2024.1640. Epub 2024 Oct 2.
Many variables in biological research-from body size to life-history timing to environmental characteristics-are measured continuously (e.g. body mass in kilograms) but analysed as categories (e.g. large versus small), which can lower statistical power and change interpretation. We conducted a mini-review of 72 recent publications in six popular ecology, evolution and behaviour journals to quantify the prevalence of categorization. We then summarized commonly categorized metrics and simulated a dataset to demonstrate the drawbacks of categorization using common variables and realistic examples. We show that categorizing continuous variables is common (31% of publications reviewed). We also underscore that predictor variables can and should be collected and analysed continuously. Finally, we provide recommendations on how to keep variables continuous throughout the entire scientific process. Together, these pieces comprise an actionable guide to increasing statistical power and facilitating large synthesis studies by simply leaving continuous variables alone. Overcoming the pitfalls of categorizing continuous variables will allow ecologists, ethologists and evolutionary biologists to continue making trustworthy conclusions about natural processes, along with predictions about their responses to climate change and other environmental contexts.
许多生物学研究中的变量——从身体大小到生活史时间到环境特征——都是连续测量的（例如以千克为单位的体重），但却被分类分析（例如大与小），这可能会降低统计效力并改变解释。我们对六个流行的生态学、进化和行为学杂志中的 72 篇近期出版物进行了小型综述，以量化分类的普遍性。然后，我们总结了常用的分类度量标准，并模拟了一个数据集，以使用常见变量和实际示例来说明分类的缺点。我们表明，对连续变量进行分类是很常见的（综述的出版物中有 31%）。我们还强调，预测变量可以而且应该连续收集和分析。最后，我们就如何在整个科学过程中保持变量的连续性提供了建议。这些内容共同构成了一个切实可行的指南，可通过简单地保留连续变量来提高统计效力并促进大型综合研究。克服连续变量分类的陷阱将使生态学家、行为学家和进化生物学家能够继续对自然过程做出可靠的结论，并对气候变化和其他环境背景下的反应做出预测。
