Name four changes that would cause an increase in an individual consumer's demand for a good or service.

To answer this question, we need to think about the "factors of demand", which are the variables that determine an individual's demand for a good or service. The four main factors to remember are as follows: The consumers preferences, the consumer's income, the price of complementary goods, and the price of substitute goods. These factors can be remember with the mnemonic PICS. With these factors in mind, we need to determine the changes to the factors that would cause a consumer's demand to increase. Firstly, a consumer will be willing to consume more of a good if their taste or preference for that good over other goods increases, so an increased preference for the good is our first change. Secondly, if a consumer has more disposable income then they will be willing and able to consume more of a good, so an increase in income is our second change. Complementary goods are goods that are bought alongside the good under consideration, for example petrol is a complementary good to cars. If the price of a complementary good declines, this increases the consumer's ability to consume the original good, so a decrease in the price of a complementary good is our third change. Substitute goods are alternatives to the good we are considering, for example cars and motorbikes are substitutes. If the substitute good's price increases, our good appears relatively cheaper and becomes more attractive, so our final change is an increase in the price of a substitute good.