In this module, the YQ Matrix measures the gap evolution between your price and the market price.
E.g. If you buy 100 euro/ton below the market price in October 2014 and 120 Euro/ton in December 2014, you did a better procurement in Dec. 2014 versus Oct. 2014 (gap increase by 20 euro/ton) independently whether prices went up or down.
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In this module, the YQ Matrix not only measures the gap evolution between your price and the market price, but also takes into account the volumes that you actually booked. This module measures you performance in absolute values (gains or losses).
E.g. A good YQ Price delta between your price and the market price on a very small volume procured will not offset a bad YQ delta on a much higher volume booked.