The topics that have been suggested as starters for this discussion include: · Smoothing; · Hard versus soft boundaries; · Geological versus assay boundaries; and Global versus local estimation. In relation to the first topic of smoothing, I did like what Craig said about smoothing because he was quite deliberate in his use of the use of the words smearing and smoothing and I think that's very important because the two concepts are quite different. It's often required that we smoothing things because sample grades don't have the same histograms as block grades. Smearing is putting metal where it shouldn't be and that's something we don't want to do. I'd like to show courtesy of Ivy Chen one of her overheads from the Tritton presentation (see Figure 6). There is no doubt that this overhead shows smoothing when you look at the copper block grades versus the copper sample grades. The sample grades have a higher variability. That may not be a problem in the least, that's a smoothing effect, it's volume variance. But if you are moving metal around or if you have significant biases we have quite a different problem. In contrast to Terry Lee (Moriah Mining Consultants) I don't actually have any problem with that, it doesn't concern me in the least. That's a support issue from a geostatisticians point of view if you like.
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