A method of verifying the performance of a size standard, formed of a plurality of size standard elements, used in a nucleic acid analysis method is provided. The verification is achieved by introducing the size standard to an analysis stage and performing a size based separation on the size standard. The size based separation defines an experimental position for each size standard element. A comparison is made as to whether or not the experimental position for the size standard element corresponds with expected position. The comparison allows a decision to be made on whether or not to use the size standard, which is dependent upon whether or not the experimental position of the size standard element corresponds with the expected position.