Group sizes in preclinical research are seldom informed by statistical power considerations but rather are chosen on practicability [1, 2]. Typical sample sizes are small, around n = 8 per group (http://www.dcn.ed.ac.uk/camarades/), and are only sufficient to detect relatively large sizes of effects. Consequently, true positives are often missed (false negatives), and many statistically significant findings are due to chance (false positives).

Group sizes in preclinical research are seldom informed by statistical power considerations but rather are chosen on practicability [1, 2]. Typical sample sizes are small, around n = 8 per group (http://www.dcn.ed.ac.uk/camarades/), and are only sufficient to detect relatively large sizes of effects. Consequently, true positives are often missed (false negatives), and many statistically significant findings are due to chance (false positives).