Within preclinical research, attention has focused on experimental design and how current practices can lead to poor reproducibility. There are numerous decision points when designing experiments. Ethically, when working with animals we need to conduct a harm-benefit analysis to ensure the animal use is justified for the scientific gain. Experiments should be robust, not use more or fewer animals than necessary, and truly add to the knowledge base of science.
Using case studies to explore these decision points, Natasha Karp and Derek Fry analysed how individual experiments can be designed in several different ways. They used the Experimental Design Assistant(EDA) graphical summary of each experiment to visualise the design differences and then considered the strengths and weaknesses of each design.
Through this format, the authors explored key experimental design issues such as pseudo-replication, blocking, covariates, sex bias, inference space, standardisation fallacy and factorial designs. Fundamentally, there is no perfect experiment and choices must be made which will have an impact on the conclusions that can be drawn. That’s why we need to understand the limitations of an experiment’s design and we should be transparent about it.

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