Good's own price: The basic demand relationship is between potential prices of a good and the quantities that would be purchased at those prices. Generally, the relationship is negative, meaning that an increase in price will induce a decrease in the quantity demanded. This negative relationship is embodied in the downward slope of the consumer demand curve. The assumption of a negative relationship is reasonable and intuitive. For example, if the price of a gallon of milk were to rise from $5 to a price of $15, that would be a big price increase. Such a significant price increase causes the consumer to demand less of that product at the price of $15 because not only is it more expensive, but the new price is very unreasonable for a gallon of milk.