Again, this undue weighting of country clearings, swallowing up New York, vitiates Professor Fisher's estimates for V, the velocity of money, for years other than 1909 and 1896. One of the elements in the calculation of V is the estimated V'.[417] Since V' is wrong, V will also be wrong. V is probably much more variable than Professor Fisher's figures would indicate. With great admiration for the ingenuity of Professor Fisher's speculations regarding V, I find too many elements of conjecture, and too many arbitrary assumptions, to give me confidence in the figure for any year. I refrain from going into any general criticism of his method of calculating V, however, contenting myself with the one clear point that, to the extent that the values of V for years other than 1909 and 1896 depend on the estimated M'V' for those years, they are less variable than they ought to be.[418] The same conclusion regarding Professor Fisher's estimates for V' have been reached, by a different method, by Professor Wesley C. Mitchell. He, too, concludes that V' is, in fact, more variable than Professor Fisher would indicate.[419] I conclude, therefore, that neither V' nor V has been correctly calculated, for years other than 1909 and 1896. I pass now to a consideration of T, the volume of trade, after which I shall consider P, the price-level, in the equation of exchange. Let us first recall the point made in the chapter on "The Equation of Exchange," that P and T, the price-level and the volume of trade, are not independent even in idea. If one is given an independent definition, the other cannot be given an independent definition. If the equation is to be true, then P must be weighted by the numbers of each item (as hats) exchanged. P is not a mere average, but is a _weighted_ average, and T is always the denominator in the formula for P. In developing statistics for P and T, therefore, this fact must be kept in mind, and the elements entering into each must coincide, and vary together year by year. In our chapter on "The Volume of Money and the Volume of Trade," we showed that the great bulk of trade is speculation. We showed that the _indicia_ of variation which Fisher[420] and Kemmerer have constructed for trade, dominated by inflexible physical items of consumption and production, give wholly misleading results for every year except the base year. They give a steadily growing, inflexible figure, with little variation from its steady path. Trade, if chiefly speculation, is highly flexible, varies enormously from year to year, waxes and wanes. This point need not be further developed. At best Fisher's figure for trade can be accepted only for one year, 1909.