◆ ARTICLES
The Library
417 articles on personal finance, investing, and the economy — filter by topic, sort, or search for the one you came for.
30 articles · page 1 of 2
◆ Spotlight
◆ CONSUMER THEORY
Consumer Surplus: The Hidden Value Markets Create
Consumer surplus is the difference between what a buyer is willing to pay and what they actually pay.
- Consumer surplus is the gap between willingness to pay and the price actually paid — the benefit a consumer captures beyond the transaction cost
- In a competitive market, consumer surplus equals the area below the demand curve and above the market price
- Monopoly pricing, taxes, and price controls reduce consumer surplus; competitive markets and lower prices increase it
◆ SUPPLY & DEMAND
Price Elasticity of Demand: How Sensitive Buyers Are to Price Changes
Price elasticity of demand (PED) measures how much quantity demanded changes when price changes.
◆ SUPPLY & DEMAND
Inside the Supply Curve: What Each Part Actually Means
The law of supply: quantity offered rises with price. A part-by-part anatomy of the curve, the six determinants that shift it, and why the time horizon…
◆ SUPPLY & DEMAND
The Shortage Problem: When Demand Outruns Supply
A shortage occurs when quantity demanded at a given price exceeds quantity supplied. Free markets resolve shortages through rising prices; price ceilings lock…
◆ SUPPLY & DEMAND
Substitutes and Complements: How Related Goods Move Together
Substitutes can replace each other — a price rise in one increases demand for the other. Complements are used together — a price rise in one decreases demand…
◆ SUPPLY & DEMAND
The Law of Demand: Why Price and Quantity Move in Opposite Directions
The law of demand states that as price rises, quantity demanded falls — and the reasons behind that relationship are more interesting than the rule itself.
◆ SUPPLY & DEMAND
Income Elasticity of Demand: What Happens to Sales When Incomes Rise
Income elasticity of demand measures how much quantity demanded changes when consumer income changes.
◆ SUPPLY & DEMAND
How Markets Find Their Price: Solving for Equilibrium
Where supply meets demand: step-by-step equilibrium math, a surplus/shortage table, and comparative statics showing exactly how curve shifts move price and…
◆ SUPPLY & DEMAND
Normal vs. Inferior Goods: How Income Changes What You Buy
Normal goods see demand rise when income rises; inferior goods see demand fall. The distinction reveals how consumption patterns shift as living standards…
◆ SUPPLY & DEMAND
Price Elasticity of Demand: Measuring How Much Buyers Actually Care About Price
PED measures how much quantity falls when price rises. Learn the formula, the midpoint method, what drives elasticity, and why it determines every pricing and…
◆ SUPPLY & DEMAND
Price Elasticity of Supply: Why Markets Don't React Overnight
PES measures how quickly producers can raise output when prices rise. Time horizon is the dominant factor — and housing and oil show exactly why it matters.
◆ SUPPLY & DEMAND
Cross-Price Elasticity: Measuring the Relationship Between Related Goods
Cross-price elasticity of demand measures how much quantity demanded of one good changes when the price of another good changes.
◆ SUPPLY & DEMAND
Surplus: When Supply Exceeds Demand and What Happens Next
A surplus occurs when the quantity supplied at a given price exceeds the quantity demanded.
◆ SUPPLY & DEMAND
Law of Demand: Why Higher Prices Mean Fewer Buyers
The law of demand states that, all else equal, as price rises the quantity demanded falls. It is one of the most robust empirical regularities in economics.
◆ COMPETITION & MONOPOLY
Producer Surplus: The Value Sellers Capture Beyond Their Minimum Price
Producer surplus is the difference between the price a seller receives and the minimum price they would have accepted.
◆ SUPPLY & DEMAND
How Prices Carry Information: The Coordination System No One Designed
Prices do more than report costs — they aggregate dispersed knowledge and coordinate millions of strangers without a central director.
◆ SUPPLY & DEMAND
Price Signal: How Markets Communicate Without Anyone in Charge
A price signal is the information a price conveys to buyers and sellers about relative scarcity, value, and opportunity.