Should sunk costs be included in a “total cost” table used to determine the optimal production quantity?

Understanding the Role of Sunk Costs in Economic Decision-Making: A Clarification

In the realm of economics and managerial decision-making, the treatment of costs—especially sunk costs—is a common point of discussion and sometimes confusion. A recent question from a high school student in South Korea highlights this debate, and exploring it can deepen our understanding of rational decision processes.

The Scenario: Including a Past Expense in Cost Calculations

Consider a business owner who has already paid ₩20,000 for opening expenses that are non-refundable. Now, the owner faces a decision: produce certain quantities of a product or produce nothing at all. Data provided includes projected revenues, material costs, and opportunity costs (such as forgone earnings from a part-time job) for each production level.

The key question: Should the initial ₩20,000 expense be included in the total costs when determining the optimal production quantity?

Teacher’s Approach vs. Standard Economic Practice

In the scenario, the teacher initially included the ₩20,000 in the total cost calculations for every production option, arguing that “a business owner still has to consider sunk costs.” Conversely, the student suggested that costs which are unrecoverable and do not affect future decisions should not be included when choosing the optimal production level.

From an economic standpoint, the standard and recommended practice is to exclude sunk costs from decision-making. This is because sunk costs, by definition, are costs that cannot be recovered or influenced by future decisions. Therefore, they should not affect the marginal or incremental decision about how much to produce, which depends solely on future costs and revenues.

Analyzing the Concept: What “Ignoring Sunk Costs” Means

When economists say “ignore sunk costs,” they mean:

• For decision purposes: Focus only on costs and benefits that will change as a result of the decision—these are relevant costs and revenues.
• For accounting/record-keeping: All costs incurred may be recorded as expenses, but only future or incremental costs influence the choice of action.

In the case at hand, including the ₩20,000 in the total cost calculation for each option does not alter the relative attractiveness of different production levels because the expense is fixed and constant across options. Both approaches—teacher’s including it and student’s excluding it—identify the same optimal production quantity.

However, for clarity and adherence to economic principles, it is more precise to exclude such sunk costs when analyzing the decision about how much to produce.

The Analogy and Its Clarification

The teacher’s analogy about buying a house and furnishing it—asking what contribution the owner made after a divorce—aims to illustrate that initial investments (like buying the house) are separate from subsequent contributions (furnishing). While somewhat interpretative, it attempts to convey that costs or contributions that have already been made should not influence current decision-making about future actions, especially when they are irrevocable.

Application to the Production Decision

Applying this analogy to the current context:

• The ₩20,000 already paid is a sunk cost.
• Deciding how much to produce now depends solely on future costs and revenues.
• The initial ₩20,000 has no bearing on the marginal profit from producing additional units.

Thus, ignoring it makes the decision process clearer and more aligned with economic rationality.

Addressing the Key Questions

1. Should sunk costs be included in the “total cost” for determining optimal output?
   In strict economic decision-making, no. They do not influence the marginal decision about how much to produce and are thus considered irrelevant.

2. Is there a confusion between relevant costs and total venture profit or loss?
   Yes. Including sunk costs when calculating the current decision’s profitability can obscure the analysis. The focus should be on incremental costs and revenues.

3. Is there a justifiable reason to consider sunk costs as part of decision-making?
   Only in non-economic contexts. For example, if the decision is whether to shut down or continue, and the sunk cost relates to previous investments, it can influence the decision about exiting. But when choosing among production levels, marginal analysis necessitates ignoring sunk costs.

4. How to discuss this with the teacher respectfully and precisely?
   Frame your question thus:
   “I understand that sunk costs are unrecoverable and should not influence our choice of production levels. Would it be more precise to exclude the initial ₩20,000 from the total cost calculations when determining the profit-maximizing quantity, since it does not affect future marginal costs or revenues? I’d like to understand whether including or excluding it aligns better with economic decision principles.”

Summary

In conclusion, the optimal approach in economic analysis is to exclude sunk costs from the calculation of marginal costs and revenues used to determine production quantity. While including such costs in accounting records is standard, decision-making should focus solely on future, relevant costs and benefits. Clarifying this distinction ensures that analyses remain aligned with core economic principles and aids in more rational decision-making.

If you’re interested in discussing this further with your teacher, framing your questions around the principle of marginal analysis, and emphasizing your desire to understand the correct application of economic reasoning, will foster a productive conversation.