Economics Lecture Notes - Wages, Opportunity Cost, and Trade

Wages, skills, and working conditions

  • Wages are tied to skills: as you build more skills, wages tend to grow alongside them.

  • Pleasant versus unpleasant conditions as wage determinants:

    • Unpleasant conditions (e.g., oil rig work: dangerous, hot, exposure to chemicals) typically command a wage premium to compensate for hardship.

    • More pleasant conditions tend to have a negative effect on wages because the disutility is lower.

  • Discrimination and wage gaps:

    • In econometric terms, a negative coefficient on a female or race indicator in a wage regression can signal discrimination.

    • In labor economics, even holding other factors constant, women are paid less on average for the same job; race can also show discriminatory effects.

  • The current lecture uses these ideas to build intuition for how models are constructed, not to conduct advanced econometric tests in this session.

Opportunity cost and the value of time

  • Opportunity cost is broader than explicit monetary costs; time is a valuable resource.

  • Robert Frost’s The Road Not Taken is used as a cultural reference to opportunity cost: choosing one path means giving up the other.

  • Quantitative example: travel choice from Amarillo to Athens by bus vs. plane

    • Bus:

    • Explicit cost = \$100; time = 16 hours (round trip)

    • Plane:

    • Explicit cost = \$200; time = 6 hours (round trip)

    • If you value your time at \$t per hour, total opportunity cost includes implicit time value:

    • Bus total cost = \$100 + 16t

    • Plane total cost = \$200 + 6t

    • Find the equality to determine when you’re indifferent:
      200 + 6t = 100 + 16t \quad\Rightarrow\quad 10t = 100 \Rightarrow\quad t = 10

    • Therefore, if your time is worth \$10 per hour, the plane and bus have the same opportunity cost; plane is preferred for saving time.

  • Another travel-cost example (money only): Taylor Swift vs. free Weeknd ticket

    • If you were planning to see Taylor Swift (value to you = \$150) and a friend offers a free Weeknd ticket (cost = \$0), the opportunity cost of seeing Weeknd is the foregone value of Taylor Swift: \$150.

  • Practical takeaway: opportunity cost includes your time, not just explicit expenditures; it can overturn seemingly cheaper explicit options.

An example of time as a paid resource (cafe model)

  • Cafés can charge for time rather than for coffee:

    • Coffee can be free; guests pay for their time spent there.

    • This forces customers to consider their own time value when deciding how long to stay.

  • Implication: time becomes a monetizable resource in microeconomic settings, illustrating opportunity cost in everyday contexts.

Trade, specialization, and the production possibilities frontier (PPF)

  • Trade creates value through specialization and comparative advantage.

  • A simple classroom demonstration used six volunteers and a random assortment of items to illustrate voluntary trade and gains from trade.

    • Each participant shared their name and how much they valued the item they received.

    • After trading, the group value rose from 28 to 35, demonstrating that voluntary trade can increase total welfare even with imperfect information.

    • The exercise highlights that gains from trade depend on differences in valuation (comparative advantages) and voluntary exchange.

  • Production Possibilities Frontier (PPF) basics:

    • The PPF shows the maximum output combinations of two goods that can be produced with a fixed set of resources.

    • Interior points are inefficient (you can increase both goods by reallocating resources).

    • Points on the frontier are efficient; you cannot increase one good without decreasing the other.

    • Points outside are unattainable with current resources.

  • Increasing opportunity costs (the curved PPF):

    • Moving along the frontier, the opportunity cost typically increases for extra units of one good.

    • Example: moving from A to B shows more of one good gained per unit of the other given the slope changes.

    • The curve indicates non-constant opportunity costs; if resources could be shifted perfectly between goods, the frontier would be a straight line (constant OC).

  • Why the curve is curved (non-linearity):

    • Some resources are better suited to producing one good than another; as you reallocate, you may start using less-efficient resources for the new production, increasing the OC.

    • For example, the first workers moved between jobs might adapt quickly, but later shifts require retraining and lower productivity, increasing OC.

  • Shifting the frontier: capital versus consumer goods and growth

    • Consumer goods satisfy current wants; capital goods help produce more in the future.

    • If an economy allocates more resources to capital goods, it can shift the PPF outward over time (growth).

    • Illustration: two-period model with pizza economy where one region invests in a new oven and can produce more in the future, shifting the frontier outward.

    • Intuition: growth comes at the cost of current consumption; you sacrifice present consumption to gain future growth.

Growth, investment, and the history of economic thought

  • The debate between Malthus and David Ricardo:

    • Malthus argued population growth would outstrip resources, leading to poverty and starvation (Malthusian doom).

    • Ricardo argued that productivity gains and technological progress allow resource use to become more efficient, preventing doom and enabling growth.

    • Modern consensus recognizes productivity and technology as key drivers of growth, supporting Ricardo’s view over Malthusian pessimism.

    • Cultural aside: a pop culture clip (Thanos in Avengers) is used to illustrate the Malthusian idea in a contemporary context.

Comparative advantage and the logic of trade (two-good, two-agent model)

  • Core idea: even if one agent is better at producing both goods (absolute advantage), there is still a gain from trade if there is a difference in relative efficiencies (comparative advantage).

  • Simple two-person example (Charlie and Frieda): two goods are apples and rabbits; time to produce depends on the person.

    • Charlie: 10 apples per hour or 2 rabbits per hour.

    • Frieda: 15 apples per hour or 1 rabbit per hour.

  • Opportunity costs (how much of the other good you must give up to produce one unit of a good):

    • Charlie:

    • OC(apples) = 2 rabbits / 10 apples = 1/5 rabbit per apple = 0.2 rabbits per apple

    • OC(rabbits) = 10 apples / 2 rabbits = 5 apples per rabbit

    • Formally: OC{Charlie}(apples) = \frac{2}{10} = \frac{1}{5} \text{ rabbit per apple}, \quad OC{Charlie}(rabbits) = \frac{10}{2} = 5 \text{ apples per rabbit}

    • Frieda:

    • OC(apples) = 1 rabbit / 15 apples = 1/15 rabbit per apple

    • OC(rabbits) = 15 apples / 1 rabbit = 15 apples per rabbit

    • Formally: OC{Frieda}(apples) = \frac{1}{15} \text{ rabbit per apple}, \quad OC{Frieda}(rabbits) = \frac{15}{1} = 15 \text{ apples per rabbit}

  • Comparative advantage conclusion:

    • Charlie has comparative advantage in rabbits (lower OC to produce a rabbit).

    • Frieda has comparative advantage in apples (lower OC to produce an apple).

  • Specialization and gains from trade (illustrative numbers):

    • Suppose a 10-hour day.

    • Without trade (each uses time on both goods), outputs are limited by their own production possibilities.

    • With specialization according to comparative advantage, each person concentrates on the good for which they have lower OC, increasing total production.

    • For example, Charlie could specialize in rabbits and Frieda in apples, yielding a larger combined output of both goods.

  • Trade as mutual gain (roommate example adaptation):

    • Suppose Sarah and Anne can either wash dishes or sweep.

    • Individual capacities:

    • Sarah: 8 sweeps or 12 dishes per period.

    • Anne: 24 sweeps or 16 dishes per period.

    • Comparative advantage:

    • Sarah’s OC in dishes is 2/3 of a sweep per dish; Anne’s OC in dishes is 2/3 of a dish per sweep (or equivalently 1.5 sweeps per dish for Anne).

    • This shows Sarah has comparative advantage in dishes; Anne in sweeping, leading to a beneficial division of labor and gains from trade.

    • The moral: specialization by comparative advantage and voluntary trade can make both participants better off than if they tried to do everything themselves.

Synthesis: linkages and practical implications

  • Nothing comes for free: to grow the economy, invest in capital goods today to shift the PPF outward, enabling higher future production.

  • Time is a resource with an opportunity cost: businesses and individuals make decisions by weighing present costs and future benefits.

  • Comparative advantage explains why trade is beneficial even when one party is more productive at producing all goods: it allows each party to specialize where they are relatively more efficient and trade for the rest.

  • The classroom demonstrations (volunteers trading items, the two-good PPF, the roommate example) illustrate the core intuition that voluntary exchange and specialization increase total welfare and resource efficiency.

Quick reference formulas and key numbers

  • Opportunity cost (OC) definitions:

    • For Charlie: OC_{Charlie}(apples) = \frac{2}{10} = \frac{1}{5} \text{ rabbit per apple}

    • For Charlie: OC_{Charlie}(rabbits) = \frac{10}{2} = 5 \text{ apples per rabbit}

    • For Frieda: OC_{Frieda}(apples) = \frac{1}{15} \text{ rabbit per apple}

    • For Frieda: OC_{Frieda}(rabbits) = \frac{15}{1} = 15 \text{ apples per rabbit}

  • Travel opportunity-cost equality example:

    • 200 + 6t = 100 + 16t \Rightarrow t = 10\,\text{hours}

  • Trade and growth intuition:

    • Specialization shifts production toward the good for which you have a comparative advantage, increasing total output.

    • Investment in capital goods today yields a higher production possibility frontier in the future, illustrating economic growth. H