The withdrawal time estimation of veterinary drugs: a non-parametric approach

The study of a veterinary drug for use in a food producing animal requires the estimation of the withdrawal time which is defined as the time when it can be assessed with a controlled risk that a given percentage (less than 100(1-alpha)%) of animals have a concentration below the Maximal Limit of Residue (MRL). A simple and understandable non-parametric method which allows the control of the risk is presented. This method does not require the assumptions needed for the correct use of the current method of estimation to be met. A simple example which illustrates the use of this method is presented.