395/1 Denarius model weight adjusted al marco
See Clive Stannard on web.me.com/clive.stannard/1/Welcome.html
The frequency of the use of gouging in the Roman Republic makes it possible to study whether weight adjustment was carried out al peso (which means that each individual flan was brought within the tolerances of the weight standard for the issue), or whether it was done al marco (which means not paying too much attention to the weights of individual coins, but ensuring that a fixed number of flans were made from a fixed weight of metal). This question can be investigated by looking at the histograms of large number of denarii, in issues known to be use gouging.
In al marco, adjustment, a block of flans is cast a little heavy; the right number of flans for the desired weight of coins is counted out (and the overall weight will, of course be, too heavy); flans that look heavy are successively picked out one by one, without too much attention to the weight and a sliver of metal is gouged off; and the gouged flans are tossed back into the block, until the overall weight is reduced to the right overall weight. The above figure models this process. As a result of adjustment al marco, the histogram is negatively skewed (the size of the upper leg has been reduced, and has high kurtosis (the centre of the histogram is higher than a normal distribution.)