Do you think that's a result of less study, Peck, or genuinely less variation? People do like their pennies... I think it is probably more to do with fewer varieties - farthings had a lower priority anyway, but the smallness of the design meant it was a better balanced strike anyway (look at how many survive in really decent grades). A similar case could be made for halfpennies, and Freeman covered them pretty comprehensively. On the other hand, if you want to do the study ... Farthings are being processed.