<P> Determinants of (Factors affecting) demand Innumerable factors and circumstances could affect a buyer's willingness or ability to buy a good . Some of the common factors are: </P> <Dl> <Dd> 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 . If the price of a new novel is high, a person might decide to borrow the book from the public library rather than buy it . </Dd> <Dd> Price of related goods: The principal related goods are complements and substitutes . A complement is a good that is used with the primary good . Examples include hotdogs and mustard, beer and pretzels, automobiles and gasoline . (Perfect complements behave as a single good .) If the price of the complement goes up the quantity demanded of the other good goes down . </Dd> </Dl> <Dd> 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 . If the price of a new novel is high, a person might decide to borrow the book from the public library rather than buy it . </Dd> <Dd> Price of related goods: The principal related goods are complements and substitutes . A complement is a good that is used with the primary good . Examples include hotdogs and mustard, beer and pretzels, automobiles and gasoline . (Perfect complements behave as a single good .) If the price of the complement goes up the quantity demanded of the other good goes down . </Dd>

Demand for a good is a measure of the relationship between