The factors that influence the decisions of household (individual consumers) to purchase a commodity are known as the determinants of demand. Some important determinants of demand are:
The price of the commodity: Most important determinant of the demand for a commodity is the price of the commodity itself. Normally there is an inverse relationship between the price of the commodity and its quantity demanded. It implies that the lower the price of the commodity, the larger is the quantity demanded and the higher the price, the lesser is the quantity demanded. This negative relationship is embodied in the downward slope of the consumer demand curve. The assumption of an inverse relationship between price and demand is both reasonable and intuitive. For instance, if the price of a gallon of milk were to increase from $5 to $15, this significant price rise would render the commodity unaffordable for some consumers, thereby leading to a decrease in demand.
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. Mathematically, the variable representing the price of the complementary good would have a negative coefficient in the demand function. For example, Qd = a - P - Pg where Q is the quantity of automobiles demanded, P is the price of automobiles and Pg is the price of gasoline. The other main category of related goods are substitutes. Substitutes are goods that can be used in place of the primary good. The mathematical relationship between the price of the substitute and the demand for the good in question is positive. If the price of the substitute goes down the demand for the good in question goes down.
Income of the Consumer: Income of the consumer is the basic determinant of the quantity demanded of a product as it determines the purchasing power of the consumer. Generally, there is a direct relationship between the income of the consumer and his demand for a product, i.e., with an increase in income, the demand for the commodity increases. However, this may not always be the case. '''Consumers' Expectations''': Consumers' expectations regarding factors such as future prices, income, and availability of goods play a crucial role in determining the demand for goods and services in the present period. For instance, if consumers anticipate a future increase in the price of a commodity, they are likely to demand a greater quantity of that commodity now to avoid paying a higher price later. Similarly, if people expect an increase in their income, they will buy more commodities in anticipation of a rise in their income. In the same way if consumers expect scarcity of certain goods in future on account of their expectation that its production may fall in future due to strike, crop failure, etc., the current demand for such goods would increase.
Consumer-Credit Facilities: If consumers are able to get credit facilities or they are able to borrow from the banks, they would be tempted to purchase certain good they could not have purchased otherwise. For instance, the demand for cars in
India has increased partly because people are able to get loans from the banks to purchase cars.
Demonstration Effect: Demonstration effect refers to the tendency of a person to emulate the consumption style of other persons such as their friends, neighbours, etc. For instance, the demand for luxury cars and expensive mobile sets has increased in recent years partly because of the desire of the people to follow the consumption style of others.
Distribution of Income: Distribution of income in the country also affects the demand for goods. If the distribution of income in a country is unequal, there will be more demand for luxury goods like cars and LED televisions. On the other hand, if the income is evenly distributed, there will be less demand for luxury goods and more demand for essential goods (necessities).
Size and Composition of population: Market demand for a commodity depends on the size and composition of the population. The population size of a country determines the number of consumers. The larger the population, the larger is likely to be the number of consumers. An increase in the size of population will increase the demand for a commodity by increasing the number of consumers and, vice versa.
Climatic factors: Demand for different goods depends on the climatic factors because different goods are needed for different climates. For instance, the demand for ice, fans, air conditioners, cold drinks, cotton clothes, etc increases in summer. Likewise, in winter, the demand for heaters, blowers, hot drinks, woollen cloths, etc increases.
Government Policy: Economic policy of the government also influences the demand for commodities. if the government imposes taxes on various commodities in the form of VAT, excise duties, etc., the prices of these commodities will increase, As a result, demand for these commodities will fall. ==Demand function equation ==