Long run in the context of "Real income"

In economics, a cost curve is a graph of the costs of production as a function of total quantity produced. In a free market economy, productively efficient firms optimize their production process by minimizing cost consistent with each possible level of production, and the result is a cost curve. Profit-maximizing firms use cost curves to decide output quantities. There are various types of cost curves, all related to each other, including total and average cost curves; marginal ("for each additional unit") cost curves, which are equal to the differential of the total cost curves; and variable cost curves. Some are applicable to the short run, others to the long run.

In economics, profit maximization is the short run or long run process by which a firm may determine the price, input and output levels that will lead to the highest possible total profit (or just profit in short). In neoclassical economics, which is currently the mainstream approach to microeconomics, the firm is assumed to be a "rational agent" (whether operating in a perfectly competitive market or otherwise) which wants to maximize its total profit, which is the difference between its total revenue and its total cost.

Measuring the total cost and total revenue is often impractical, as the firms do not have the necessary reliable information to determine costs at all levels of production. Instead, they take more practical approach by examining how small changes in production influence revenues and costs. When a firm produces an extra unit of product, the additional revenue gained from selling it is called the marginal revenue (${\displaystyle {\text{MR}}}$), and the additional cost to produce that unit is called the marginal cost (${\displaystyle {\text{MC}}}$). When the level of output is such that the marginal revenue is equal to the marginal cost (${\displaystyle {\text{MR}}={\text{MC}}}$), then the firm's total profit is said to be maximized. If the marginal revenue is greater than the marginal cost (${\displaystyle {\text{MR}}>{\text{MC}}}$), then its total profit is not maximized, because the firm can produce additional units to earn additional profit. In other words, in this case, it is in the "rational" interest of the firm to increase its output level until its total profit is maximized. On the other hand, if the marginal revenue is less than the marginal cost (${\displaystyle {\text{MR}}<{\text{MC}}}$), then too its total profit is not maximized, because producing one unit less will reduce total cost more than total revenue gained, thus giving the firm more total profit. In this case, a "rational" firm has an incentive to reduce its output level until its total profit is maximized.

The iron law of wages is a proposed law of economics that asserts that real wages always tend, in the long run, toward the minimum wage necessary to sustain the life of the worker. The theory was first named by Ferdinand Lassalle in the mid-nineteenth century. Karl Marx and Friedrich Engels attribute the doctrine to Lassalle (notably in Marx's 1875 Critique of the Gotha Program), the idea to Thomas Malthus's (1798) An Essay on the Principle of Population, and the terminology to Goethe's "great, eternal iron laws" in Das Göttliche.

It was coined in reference to the views of classical economists such as David Ricardo's law of rent, and the competing population theory of Thomas Malthus. It held that the market price of labor (which tends toward the minimum required for the subsistence of the laborers) would always, or almost always, reduce as the working population increased and vice versa. Ricardo believed that this happened only under particular conditions.