Costs of the Firm Lecture Notes

This flashcard set covers the fundamental concepts of production and costs, including input choices, cost functions, returns to scale, and optimal input combinations.

Production technology

A way of describing how inputs can be transformed into output, represented by the production function.

Cost constraint

Refers to the budget faced by the firm with reference to the price of inputs such as wages and rental.

Input choices

The decision firms make regarding how much of each input to use, such as the optimal amount of labour and capital to be hired.

Short run

A period of production in which at least one input, normally capital, is assumed to be fixed.

Long run

A period of production in which all inputs are variable and can be adjusted.

Marginal product of labour ($MP_L$)

The additional output produced by the next worker, calculated as $\frac{dQ}{dL}$. Initially it increases due to specialization, then eventually decreases because capital is fixed.

Diminishing marginal product of labour

A situation where continuing to increase labour results in the next worker producing less output than the previous worker, meaning total output increases at a decreasing rate.

Fixed Cost ($FC$)

A production expense that is independent of the level of output, such as the cost of building a factory.

Variable Cost ($VC$)

A cost that varies with the quantity of output produced, increasing as output increases.

Total Cost ($TC$)

The sum of fixed costs and variable costs, expressed as $TC = FC + VC$.

Marginal Cost ($MC$)

The extra cost incurred to produce one more unit of output, calculated as $MC = \frac{dTC}{dq}$. MC cuts average cost at its minimum point.

Increasing returns to scale ($IRS$)

Occurs when scaling up all inputs by a factor of $t$ results in output increasing by more than $t$, possibly due to specialization or economies of scale.

Decreasing returns to scale ($DRS$)

Occurs when scaling up all inputs by a factor of $t$ results in output increasing by less than $t$, potentially due to management inability or coordination problems.

Constant returns to scale ($CRS$)

Occurs when scaling up all inputs by a factor of $t$ results in output increasing by exactly $t$, implying constant average and marginal costs.

Isocost

A line representing the combinations of two inputs, labour ($L$) and capital ($K$), that can be hired with a specific budget ($C_0$) given prices ($w_0, r_0$); its equation is $C = wL + rK$.

Isoquant

A curve showing combinations of labour ($L$) and capital ($K$) that produce the same quantity of output ($Q$).

Marginal rate of technical substitution ($MRTS$)

The rate at which capital can be substituted for labour while holding output constant along an isoquant, defined as the absolute slope of the isoquant where $MRTS = \frac{MP_L}{MP_K}$.

Economic profit ($\pi$)

The difference between total revenue and total cost, calculated as $\pi = pq - (wL + rK)$, where $p$ is price and $q$ is quantity.

Marginal Revenue Product of Labour ($MRP_L$)

The money value of the marginal product in a perfectly competitive market, calculated as $MP_L \times P$. Firms hire until $MRP_L = w$ to maximize profit.