title: The interaction of statistical significance, biology of dose-response and test design in the assessment of genotoxicity data.
abstract: The most useful function of statistical significance in genetic toxicology is to separate weakly positive from negative data. To achieve this objective, the experimental system, design and analysis must be considered as a whole and not as separate entities. Assumptions underlying statistical methods should be checked for applicability to the biology of the test. The number and arrangement of samples and dose levels must be organized to suit the selected statistical method. The number of observations in the test and in each sample will depend on the smallest increase of biological importance which should be detected as significant (at a selected value for alpha error) and the maximum acceptable chance of failing to detect this increase as significant (beta error). Generally, a few dose levels and a high degree of replication are desirable with a repeat test if practical. In the analyses of data it is particularly important to adapt the statistics if there are multiple comparisons. Even after correct determination of significance, interpretation can be difficult because of possible experimental artefacts and chance errors plus the impossibility of proving a negative result.
authors.affiliation: Beecham Pharmaceuticals Research Division, Essex, UK.
authors.forename: I D
authors.initials: ID
authors.lastname: Mitchell
mesh_terms: D003627:Data Interpretation, Statistical; D003661:Decision Support Techniques; D009152:Mutagenicity Tests / Q000379:methods*; D012107:Research Design; D013269:Stochastic Processes