 Module 21, change in equilibrium due to factors other than price. Consumers equilibrium also changes whenever there is a change in prices, whenever there is change in factors other than price of that particular commodity. And because of that change in equilibrium, because of factors other than price, there is also change in demand for that particular commodity. For example, demand for a particular good also shifts due to change in prices of other related commodities. Those other related commodities may be substitutes or complement. In fact substitutes are those commodities for which case price of a commodity increases. And for other commodity will also increase. It indicates two commodities are substitutes while two commodities are complement if price of one commodity increases and there is a decrease in quantity demand of other commodity. Then those two commodities are complement. For example, if we assume burger and cold ring are complement. If price of burgers increases then there is a decrease in demand for cold rings. Similarly, if we assume the burger and cold rings are substitutes in that case if price of burgers increases demand for cold rings will increase. And if we replicate this concept with reference to our example where consumer is using only apples and oranges to maximize his satisfaction. And we consider apples and oranges as complement. Then rise in price of apples would lead a fall in quantity demand for oranges. In fact, there is fall in quantity demand for both commodities because of price increase in price of one commodity. If two commodities are complement. But if we assume apples and oranges are substitutes then rise in price of apples would cause a rise in quantity demand of oranges and a decrease in demand for apples. In this diagram we are reporting the impact of change in price of apples on demand for oranges. But in this case we are considering oranges and apples as complement. If we assume there is increase in price of apples because of that increase in price of apples we can see there is a decrease in demand for apples. And at the same time because of increase in price of apples there is also a decrease in demand for oranges. The demand curve for oranges shift leftward. And this leftward shift in the demand of oranges is because of complementary nature of oranges with reference to apples. Similarly, if we assume apples and oranges as substitutes and we have already see if there is a change in price of apples there is change in consumers equilibrium even if there is no change in income and no change in price of oranges. But ultimately it will effect demand for apples and oranges. So change in demand for apples and oranges is because of change in consumers equilibrium and that change in consumer equilibrium is because of change in price of one commodity. In this case if we assume there is an increase in price of apples and because of that increase in price of apples we can observe an increase in demand for oranges. Demand for there is an upward shift of the demand curve for oranges. Then this association given price of one commodity increases and demand for other commodity increases it indicate two commodities are substitutes. It might be possible that two commodities are neutral commodities if price of one commodity changes it might be possible it has no impact on the demand for other commodity. If we assume apples and fuel are neutral goods if price of apples increases it might be possible it has no impact on demand for fuel. If it has no impact on the demand for fuel then we can say apples and fuel are independent from each other. Hopefully after completion of this module you are very much clear about substitutes, complement and neutral goods. Substitutes are those goods for which change increase in price of commodity results in increase in demand for other commodity. And commodities are complements if increase in price of one commodity decreases demand for other commodity. And two commodities are independent or two commodities are independent if change in price of one commodity has no impact on the demand for other commodity. And this all change is because of change in consumers equilibrium and that change in consumer equilibrium is because of change in price of commodities. Thank you very much.