BNF 1113 Microeconomics_Theory of cost
Introduction to Cost Theory
Under production theory, we look into the laws of production and the relationship between input and output expressed in physical quantities. However, business decisions often rely on money values of inputs and outputs. Transitioning from production to cost theory, we will examine how production costs change with output levels. The cost function, which relates cost to output, depends on production conditions and factor prices. The cost of production is a crucial factor that influences the supply of a product, and firms aim to minimize production costs for a given output level.
Cost Functions in Microeconomics
Types of Cost Functions
Short-Run Cost Function: Reflects costs incurred when some inputs are fixed.
Long-Run Cost Function: All inputs are variable, allowing firms to adjust their scale of production.
Concepts of Costs
Accounting Costs: These are the actual payments for factors of production, including wages, rent, and material costs.
Economic Costs: Include both accounting costs and implicit costs (opportunity costs).
Economic Costs = Accounting Costs + Implicit Costs
Opportunity Cost
Opportunity cost represents the potential income lost due to choosing one alternative over another. It plays a significant role in economic decision-making, as firms must evaluate the next best alternatives available.
Business Costs and Profit
Business Costs
Business costs encompass all expenses incurred by a firm, including both explicit and implicit costs. These costs form the basis for determining profit.
Explicit Costs: Direct payments made by the business.
Implicit Costs: Indirect opportunity costs of resources that could have been used elsewhere.
Economic Profit = Total Revenue - Economic Costs
Cost Concepts: Private vs. Social Costs
Private Costs: Costs incurred by an individual or firm, covering both explicit and implicit costs.
Social Costs: Broader costs to society from production, including external costs not paid by the firm.
Short-Run Cost Analysis
Fixed and Variable Costs
Fixed Costs: Payments that do not change with output levels (e.g., rent, insurance).
Variable Costs: Costs that vary directly with output levels (e.g., materials, wages).
Cost Equations
Total Cost (TC) = Total Fixed Cost (TFC) + Total Variable Cost (TVC)
Average and Marginal Costs
Average Fixed Cost (AFC): Total fixed cost divided by output produced, showing fixed cost per unit of output.
Average Variable Cost (AVC): Total variable cost divided by output, generally decreasing at first then increasing.
Average Total Cost (ATC): Sum of average variable and average fixed costs.
Marginal Cost (MC): Additional cost incurred from producing one more unit.
Cost-Output Relationships
Short-Run Relationships
In the short run, as production increases, total costs rise. The behavior follows the law of diminishing returns, where output increases at varying rates.
TC increases at increasing or decreasing rates based on the production level.
Long-Run Relationships
In the long run, all inputs become variable. The firm optimizes its production by adjusting all factor inputs. The long-run cost-output relationship illustrates how firms can change their scale to affect total output.
Long-Run Cost Curves
Long-Run Total Cost Curve (LTC): Reflects the lowest cost of producing different output levels when all factors are variable.
Long-Run Average Cost Curve (LAC): Shows the average of the total cost when production scales change, typically shaped like a U, indicating initial economies of scale followed by diseconomies.
Long-Run Marginal Cost Curve: Related to the slope of the LTC, representing additional cost for producing an additional unit.
Conclusion
Understanding the cost functions and their behavioral characteristics is vital for firms in making informed production and financial decisions. These concepts form the foundation for analyzing costs in microeconomics and apply to real-world situations in business management.