Abstract: From data that includes prices and unit sales of an item of commerce for a succession of time periods during which the item was sold, a relationship is derived that represents variation of unit sales of the item as a function of price and time of sale. A maximum profit is predicted by optimizing the price or inventory or both over time in accordance with the relationship. The optimized price or inventory or both over time are used in connection with making price decisions or inventory decisions or both with respect to marketing the item of commerce. A group of the data is aggregated, the group being chosen so that the aggregated data for the group will have an enhanced signal-to-noise ratio with respect to information about sales trends. The aggregated data for the group is analyzed for use in making price decisions with respect to marketing the items of commerce.