title: The chances of false negative results in conventional toxicology studies with rats.
abstract: Data from conventional rat toxicology studies from 2 centres are used to estimate the coefficients of variation of organ weights, haematology and blood chemistry characteristics commonly measured in such studies. Charts, based on simple statistical formulae, are provided which enable this information to be used to indicate the probability of failing to detect a treatment effect of a given magnitude as statistically significant. The results, for a study with 20 rats/treatment group, when the treatment causes a change of 10% in the characteristic, indicate wide variability in the false negative error rate. With some characteristics (e.g. haemoglobin, total protein, brain weight, red blood cell count) the false negative rate is less than 0.1%, but for others (e.g. white blood cell count, glutamic-pyruvic transaminase, pituitary weight, cholesterol) it is in excess of 70%.
mesh_terms: D000818:Animals; D001774:Blood Chemical Analysis; D005188:False Negative Reactions; D005260:Female; D007958:Leukocyte Count; D008297:Male; D008433:Mathematics; D051381:Rats; D012107:Research Design; D014116:Toxicology / Q000379:methods*