Economics Basics: Scarcity, Prices, and Asset Valuation

The study is grounded in scarcity; this is the core focus of economics.
Question posed: What is economics? Traditionally introduced in the first chapter of textbooks.
The setting for analysis is economic, where scarcity drives choices and trade-offs.

In the US context, terms like firms are used in discussing economic actors; an asset can be a stock.
A stock is an asset (as defined previously in the course/book).
Two primary reasons investors respond to stocks:
- Receive dividends (cash flows from ownership).
- Sell the stock later to realize a capital gain (price appreciation).
An asset’s returns come from these two channels: dividends and price appreciation from selling.
An investor must separate investment objectives: some stocks are more secure (less risky), while others are more speculative (riskier).
Different assets illustrate diversification needs and risk tolerance (e.g., Bitcoin vs. a physical asset like automobile frames).
Example to illustrate asset specificity:
- Bitcoin is a digital, highly liquid asset with different risk/return characteristics compared to a physical frame produced for a GM plant.
- Not every frame is produced for any old purpose; asset quality and use-case matter (asset specificity and constraints).

The core idea: everything has a price in an economic setting.
A common caricature of economists: an economist is someone who knows the price (implies price signals encapsulate information about value).
Slopes and calculus connect to economics: slopes of functions (marginal changes) are derivatives.
- In notation: the slope is the derivative, written as f'(x) = rac{df}{dx}.
Calculus requires the right kind of functions and data to be applicable; not every situation yields a meaningful calculus model.

Quantities and prices are measured in real numbers, even though real-world transactions involve discrete items (e.g., one car).
In economic modeling, we often use simplified or toy models to study core relationships.
Example concept: one toy unit (e.g., a single car) is used to illustrate price-quantity relationships in a clean, abstract way, even though it diverges from real-life complexity.

If a bond promises to pay $100 in the future and the current price is $80, the investor is effectively earning a gain of $20 by waiting for the future payoff (implicit yield exists).
Key intuition: when the current price of a bond falls, the yield to maturity on that bond rises, increasing the eventual return relative to the price paid.
To formalize with a simple one-period bond:
- Present value relationship: P0 = rac{FV}{1 + r} where P0 is the current price, FV is the future value paid at maturity, and r is the one-period yield.
- Given FV = 100 and current price P0 = 80, the implied yield is: r = rac{FV}{P0} - 1 = rac{100}{80} - 1 = 0.25 ext{ (or 25%)}.
- If the price falls to P0' = 70, the new yield is: r' = rac{FV}{P0'} - 1 = rac{100}{70} - 1 \approx 0.4286 ext{ (or 42.86%)}.
General present-value perspective can also be written as:
- P_0 = rac{FV}{(1 + r)^t} for a multi-period bond with maturity in t periods,
- or equivalently, FV = P_0 (1 + r)^t.
Takeaway: as the price today falls, the return (yield) on the bond increases; this is the basic price-yield relationship in fixed-income finance.

Prices convey information about value, risk, and returns; investors must interpret them in the context of objectives and risk tolerance.
The distinction between secure and speculative assets guides portfolio construction and diversification strategies.
Asset specificity highlights that some assets are tailored to particular uses or contexts, affecting their liquidity and pricing.
Modeling with real numbers and simplified units helps clarify fundamental concepts like marginal change, return, and present value, even though real markets are more complex.
The discussion links foundational principles of economics (scarcity, prices, and incentives) with financial concepts (dividends, capital gains, yield, and risk).