The present invention relates to a method and an apparatus for batching items (9, 11) of non-uniform weight into batches fulfilling certain weight criteria. The items (9, 11) are conveyed across a scale (10) registering the weight of each item individually, and subsequently, the items (9, 11) are combined into batches. In particular, the invention relates to a method of analyzing process deviations in a batching process, e.g. to detect faults in a batching system or in order to improve a batching process flow. One sophisticated application of the invention is to include a simulation of the batching process to accurately predict the results for the pack-sizes on demand and recommend the optimal ones to the operator.