Unit 2: Supply and Demand
In this unit we introduce the ceteris paribus assumption, which is crucial to building correlations among economic variables. When using ceteris paribus, we assume that all variables - with the exception of those in explicit consideration - will remain constant. We then examine the supply and demand models and the resulting market equilibrium that occurs where the supply curve and the demand curve intersect. We also explore what causes movements along the curve and the set of factors that cause the curves to shift, affecting both price and quantity, before discussing the meaning and significance of elasticity.
Next, we explore what happens when a market fails to produce a reasonable equilibrium. This situation typically occurs when either the market is not competitive or complete, or its participants are ill-informed. We evaluate various ways the government can address these failures and begin to understand the intricate relationship between government and economics.
Completing this unit should take you approximately 12 hours.
Upon successful completion of this unit, you will be able to:
- define demand, supply, and market equilibrium;
- determine the equilibrium in a market under situations that cause shifts in demand and supply that affect changes in prices and quantities;
- apply elasticity of demand and elasticity of supply to scenarios where they cause changes in prices and incomes; and
- analyze how the market can be manipulated through price controls.
2.1: The Ceteris Paribus Assumption
- Read this brief text to learn the formal definition of ceteris paribus. As a practice activity, identify a variable and list the multiple factors that may be influencing it. For example, say you are planning to request an increase in your salary. What are the factors that influence your salary? Do you think you can attribute the change in your salary to any one of these factors if all of the factors influencing it were simultaneously changing?
2.2: Demand
- Read this section to learn about the theory of demand. Attempt the "Try It" problem. Use the data from the text to practice constructing and drawing the demand curve on your own, either on a paper or in Excel. Take a moment to read through the stated learning outcomes for this chapter of the text, which you can find at the beginning of each section.
- Read this to learn about how factors that affect demand, such as income and change in tastes, are graphed as shifts of the demand curve. Make sure to answer the "Try It" questions.
- Watch this video about the law of demand for understanding consumer behavior. The basic premise of the law of demand, as the video explains, is that if a consumer sees the price of product rising then this consumer will be less likely to buy that product or will lower the amount of consumption of that product. Think about the rise of gasoline prices and the effect it has on the average consumer as most consumers will try to reduce their gasoline consumption, assuming that one's income and wealth remains the same.
- Watch this video about the price of related products and how the demand curve for a product gets affected. Examples of related products are those that can substitute for each other like oranges and apples. If the price of apples increases and the price of oranges remains the same, then consumers are more likely to buy less apples and more oranges.
- Watch this video about how changes in income, population, and preferences affect the demand curve. Make sure to understand the difference between "a change of where we are in the demand curve" and "a shift of the demand curve".
- Watch this video about normal and inferior goods to better understand the different types of consumer products. Make sure that you go back to the reading in Unit 2.2 to learn about the terms normal and inferior goods. The term inferior good usually relates to the standing in quality that a product has in society. For example, fast food is normally considered to be on a lower quality standing than restaurant food. Thus, when the incomes of people rise, less fast food is consumed and more of restaurant food is consumed instead, making fast food the inferior good and restaurant food the normal good.
- Watch this video about inferior goods in order to see the relation between price and quantity demanded. Remember that inferior goods are considered to be on the low quality level in society and consumers would want to purchase less of them as their incomes rise and they are able to afford better quality products.
2.3: Supply
- Read this section to learn about the theory of supply. Attempt the "Try It" problem. Use the data from the text to practice drawing the supply curve on your own, either on paper or in Excel. Take a moment to read through the stated learning outcomes for this chapter of the text, which you can find at the beginning of each section. These outcomes should be your goals as you read through the chapter.
- Read this section to learn more about how factors that affect supply, such as increases or decreases in the costs of production, are graphed as shifts of the supply curve. Make sure to answer the "Try It" quiz questions.
- Watch this video about the law of supply as it is graphed with an economic model. Make sure to go back to the main reading Unit 2.3 to learn that the law of supply states that a rise in prices makes producers want to sell more of that product in order to earn more revenue from their sales.
- Watch this video about to see how factors affecting supply make shifts of the supply curve. Remember that the main factors that affect supply are: land, labor, and capital.
2.4: Market Equilibrium
- Read this section to learn how demand and supply interact with one another to determine prices and quantities that may or may not be optimal. Attempt the "Try It" problem. Take a moment to read through the stated learning outcomes for this chapter of the text, which you can find at the beginning of each section. These outcomes should be your goals as you read through the chapter.
- Watch this video about market equilibrium with the use of a graph so you can see the demand and supply curves come together in the market.
- Watch this video about how shifts of the demand or supply curves affect the market equilibrium point.
- Read this section to learn about some applications of the demand and supply model. Attempt the "Try It” problem.
- Read this article to learn more about how changes in supply and demand affect the market price equilibrium. Make sure to answer the "Try It" questions.
- Read the sections on Demand, Supply, Market Equilibrium, and Government Intervention and Disequilibrium for a mathematical exposition of the demand and supply model, clicking through to the next when you have finished each page. The chapter also covers price ceilings and price floor analysis as well as quantity regulations.
2.5: Manipulating the Market: Price Controls
- Read this section to learn why the government sometimes chooses to control prices. Attempt the "Try It" problem. Take a moment to read through the stated learning outcomes for this chapter of the text, which you can find at the beginning of each section.
- Read this section as a review of price floors and price ceilings. Try solving the "Self-Check Questions".
- Read this section to learn more about how price floors and price ceilings create inefficiencies in the market. Pay special attention to the concepts of Consumer Surplus, Producer Surplus, and Social Surplus and how they are affected due to price controls. Try solving the "Self-Check Questions".
- Now, let's attempt several practical problems related to price controls. Answer the "Try It" questions here.
- Watch this video about minimum wage and price floors with the use of a graph to understand the effect on the labor market.
2.6: Elasticity
- Read this chapter to learn about the concept of elasticity. Be sure to read Sections 5.1-5.4 following the introduction.
- Read this chapter to learn about the concept of elasticity. Be sure to read all the sections in this chapter (Sections 5.1-5.4) following the introduction.
- Watch this lecture, focusing on both how elasticity is calculated as well as its potential implications for health care. Consider if you agree or disagree with the possible social and health implications of changing the overall elasticity of demand for national health systems.
- Read this section about price elasticity when there is a change along the demand curve. Make sure to back to the main reading in Unit 2.6 as it explains the concept of elasticity. Also, make sure that you understand the concept of "price elasticity of demand", which is about how the percentage change in the price of a product affects the amount of quantity demanded but measured as a percentage change.
- Watch this video about how the price elasticity of demand is depicted with the use of a graph. Make sure that you understand when the elasticity of demand is elastic, inelastic, and unit elastic.
- Watch this video to understand how to use the formula for calculating the elasticity of demand. You can also refer to the previous video listed for this unit titled "Price Elasticity of Demand".
- Watch this video to understand how the constant unit elasticity looks like as the demand curve. Note that the demand curve is not straight in the case of a constant elasticity of demand.
- Watch this video about how total revenue for the producer is affected depending on the elasticity of demand for a product.
- Watch this video about to learn about the effect on the total revenue for a producer when the demand elasticity changes. The price elasticity of demand is oftentimes used a way to calculate changes in total revenuw for a producer.
- Watch this video to learn how to calculate the cross elasticity of demand for products that are complements and for products that are substitutes. You can think of complemenatry products like popcorn and a movie ticket, when the price of one goes up, the quantity demanded goes down for both, thus their cross price elasticity will show a negative relationship. The same applies for products that are substitutes, like popcorn and candy at a movie theater. When the price of popcorn rises, the quantity demanded for popcorn decreases but for candy it goes up, thus their cross price elasticity will show a positive relationship.
- Watch this video about the concept of elasticity of supply. Just like the elasticty of demand, the elasticity of supply relates the percentage change in the quantity supplied to a percentage change in the price.
- Watch this video to learn more about how to calculate the price elasticity of supply using the geometric approach. You should also go back to the reading for Unit 2.6 to learn in detail about the formulas used.
Read this article on how to estimate elasticity. Make sure to answer the "Try It" questions.
- Watch this video to learn about how taxes relate to a perfectly inelastic demand. Remember that a perfectly inelastic demand curve is one where the quantity demanded is constant regardless of changes in the price.
- Watch this video to learn about how taxes relate to a perfectly elastic demand curve, which is one that is very sensitive to changes in prices.