When we draw a supply curve, we assume that other variables that affect the willingness of sellers to supply a good or service are unchanged. It follows that a change in any of those variables will cause a change in supply , which is a shift in the supply curve. A change that increases the quantity of a good or service supplied at each price shifts the supply curve to the right. That will reduce the cost of producing coffee and thus increase the quantity of coffee producers will offer for sale at each price. Continue reading “Suppose, such as, that the cost of fertilizer drops”