═══════════╤═══════════╤═══════════╤═══════════╤═══════════╤═══════════ │ Basic │Eight-year │ November, │ Pct. │New Index. │ Index. │ period │ 1917, │ increase │ │ │ average. │ price. │Nov., 1917,│ │ │ │ │over 8-year│ │ │ │ │ period. │ ───────────┼───────────┼───────────┼───────────┼───────────┼─────────── Corn │ 19│ $1.107│ $3.089│ 179│ 53.01 Mill-feeds │ 19│ 1.306│ 2.3655│ 81.1│ 34.41 Hay │ 35│ .557│ .780│ 40│ 49.00 Labor │ 27│ │ │ 50│ 40.50 ───────────┼───────────┼───────────┼───────────┼───────────┼─────────── │ 100│ │ │ │ 177 ───────────┴───────────┴───────────┴───────────┴───────────┴─────────── “The average price of milk per one hundred (100) pounds for the month of November, from 1908 to 1915, inclusive, was $1.768. Applying the new index ratio of 1.77, the November, 1917, price would be, therefore, $3.13. In the same manner, the price for any month may be determined by taking the average price over the eight-year period for that month and multiplying it by the index figure, 1.77. It will be noted that by the use of this method the _ratio_ of the costs of feed and labor between the average of the eight-year period and the November, 1917, period, is used rather than the actual prices of the commodities. “The average monthly prices of milk per hundred pounds over the eight-year period were as follows: November, $1.768; December, $1.812; January, $1.781; February, $1.737; March, $1.60; April, $1.406; May, $1.15; June, $1.017. Applying this index, 1.77 November price, to these figures: November, $3.13; December, $3.20; January, $3.15; February, $3.07; March, $2.83; April, $2.49; May, $2.04; June, $1.80.” [Illustration: Illustrating when Chicago milk prices have been above and below their ten-year average ratio to feed and labor prices. ]