Statistics and the Issue of Animal Numbers in Research

The application of statistical science in helping to determine the optimum number of animals to use in experiments and in justifying the proposed number of animals is under used. Without federal guidance, the standards that constitute adequate justification are extremely variable and inconsistent from one Institutional Animal Care and Use Committee to the next. A unified approach for determining appropriate numbers of animals and ways to justify the proposed number of animals in many study protocols is provided here. This represents a first important step toward an improvement in the consistency with which researchers deal with the issue of animal numbers.