This document provides guidance to study organizers involved in designing, executing and evaluating collaborative studies for multi analyte methods developed by the various working groups of the CEN/TC 327 Animal feeding stuffs: Methods of sampling and analysis . The main goal of such studies is to determine the reproducibility standard deviations for the analytes investigated in the selected matrices. They are calculated from the repeatability and the between-laboratory standard deviations determined from the study data. An additional goal may be the determination of the trueness (whenever possible).