Abstract: A stack of signatures is delivered to a weighing platform which measures bundle weight. A stored bundle weight is subtracted from the measured bundle weight to yield a difference which is compared against the stored reference weight of an individual signature. If the difference is a multiple of the weight of an individual signature, an indication of a count error is given. If the aforesaid difference is greater than the weight of an individual signature but is not an integral multiple of that weight, an indication of a possible combination error is given. If the difference is less than the weight of an individual signature, a recalibration is initiated to substitute the reference weight per unit with a new value prior to initiation of the next measuring cycle. In the presence of a combination error pattern, a manual count check is made on the subsequent sample to insure a correct count and a recalibration is then initiated.