Manifestly, the weak point in the ratio method of determining cost of producing crops is the character of the basic period. Did the crops actually sell during the basic ten-year period for cost of production? Manifestly, in some years they sold for less, and in some years they sold for more. As an average of the entire ten-year period, they must have sold for at least cost of production, or farmers would gradually have reduced their acreage of the particular crop under consideration, or else gone out of business entirely. As a matter of fact, in the ten-year period under consideration, 1897–1906, land values were constantly advancing. It would seem, on the whole that this particular ten-year period is a fair one to use, and that as an average of these ten years crops sold for approximately cost of production, no more, no less. It is always conceivable that over long periods of time there might have occurred changes in supply or demand conditions that would make the basic ten-year period altogether false for the purpose of comparison. For example, in the case of oats, it is conceivable that tractors, trucks and automobiles might so displace horses as to make the city demand for oats decidedly less than during the ten-year period extending from 1897 to 1906. The oats acreage might therefore be considerably decreased, and oats be produced in large quantities only in those sections especially adapted to growing oats. It is conceivable, therefore, that the ratio method may possibly give the cost of oats production at rather too high a figure, a figure impossible of realization, one year with another. In the case of standard crops, however, there is remarkably little change in either supply conditions or demand conditions. Methods of producing corn are pretty well standardized. The market for corn is almost equally stable. It is believed that the ratio method of determining cost of corn production will be approximately accurate for the next fifty years. CONSUMERS’ RATIOS During the past fifty years, a number of people have set themselves to work to measure the shifting economic tides with index numbers. The more complete of these index numbers really undertake to measure the changing value of the dollar. In July of 1914, for instance, Dun’s index number was $119.71, which meant that it required $119.71 to buy a certain given amount of wheat, corn, oats, pork, beef, butter, eggs, wool, hides, pig iron, lumber, petroleum, etc. On September 1, 1919, it required $238.34 to buy these same goods. The dollar of July of 1914 had become worth about 50 cents in September of 1919, in its ability to buy wholesale products. The consumer, in his buying, has certain choices. The man who thinks pork is too high in price can shift to beef or mutton; or he can leave meat altogether out of his ration and secure the needed nutrients in dairy or poultry products.