Animal stress studies rarely reported planning around a biologically meaningful effect
A review of animal studies found that only one article reported using a biologically meaningful effect to plan sample size. The result concerns research reporting, rather than stress treatments or human health.
Based on the published abstract. The full paper may contain additional methods, results and limitations.
The 30-second takeaway
The review asked whether animal stress researchers planned sample sizes around an effect large enough to matter biologically. Only one reviewed article reported doing so, and most offered no sample-size justification. This identifies a reporting gap in experimental design; it does not prove that every unreported decision was absent or that the underlying findings were wrong.
The abstract does not describe the search period, animal species or detailed assessment criteria. Its central result is what articles reported, so it cannot fully reveal how researchers actually made planning decisions that were left undocumented.
Why effect size enters planning
An effect size describes the magnitude of a difference being studied. The authors argue that planning should focus on a biologically meaningful magnitude, alongside choosing enough animals to detect it without using unnecessarily large numbers.
A null result can still inform
The authors emphasize that a study designed to detect a meaningful effect can be useful even when its results do not support the hypothesis. Statistical significance alone therefore does not capture their proposed standard for planning and interpreting experiments.
The original publication
Are biologically meaningful effect sizes a factor in study design? A systematic review of translational chronic variable stress studies.
Jordan C, Romanò N, Menzies J
Exp Physiol · 2026
- PubMed ID
- 40632599
- Record checked
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