REFINEMENTS IN EXPERIMENTAL PROCEDURES
Refinement as part of the 3Rs concept refers to measures aimed at minimizing harm to research animals. Whether any harm imposed on animals is ethically justifiable, however, depends on the expected benefit of the research. Unless a study produces results that are scientifically valid and reproducible, animals may be wasted for inconclusive research. Recent evidence indicates considerable risks of bias across all areas of animal research, questioning both scientific validity and reproducibility. Risks of bias are caused by flaws at all levels of research, including the design, conduct, analysis and reporting of experiments. Thus, studies may be based on samples that are too small or idiosyncratic; they may lack independent replicates, violate good research practice (e.g. randomization, blinding, sample size calculation), and use inappropriate statistics; or they may report results selectively or not at all (publication bias). All of this may compromise the scientific validity of results reported in the literature, thereby exacerbating the current “reproducibility crisis”. I will provide a systematic overview of risks of bias and measures to avoid them and highlight knowledge gaps that need to be filled by future research.