November 30, 2011

Engineering Economy or Engineering Economics: Economic Decision Making by Engineers

Engineering Economy: An Explanation

An engineering economy study involves technical considerations and it is a comparison between technical alternatives in which the differences between the alternatives are expressed so far as practicable in money terms (Grant and Ireson, 1960).
Every engineerng decision must be subjected to the question "Will it pay?"
The late General John J.Carty, Chief Engineer of the New York Telephone Company, had asked three questions for every engineering proposal that came to him for review.

1. Why do this at all?
2. Why do it now?
3. Why do it this way?

The first question makes an enquiry regarding profit. In business you do a thing because it is profitable to do so.
The second asks whether the person proposing the investment or expenditure has considered the time alternatives. Can we postpone the investment/expenditure and make more profit?
The third question forces the concerned person to consider all other alternatives to the issue at hand and certify that the solution proposed is the most profitable proposal.

Thus General John Carty made sure that engineering economy studies were done by his technical departments.


Economic Decision Making

Every dollar an executive proposes to spend or proposes not to spend has to be subjected to economic decision making. If an executive decides to keep a machine in service even though it has frequent breakdowns, giving more number of defective items and consuming more energy, he is making an economic decision. A decision to do nothing is a decision to continue the present production equipment or the system and to reject all alternatives, those which were known and those which were not searched for if he has not searched for them.

Most executives agree that the decision to invest Rs. 5,00,000 for the purchase of a new machine is a typical example of an economic decision. But they do not consider their choice not replacing a machine as an economic decision.

Executives are Unprepared for Economic Decision Making

George A. Taylor in his text book, Managerial and Engineering Economy emphasizes that executives are unprepared for their responsibility in generating and examining alternatives by economic criteria. Most of the executives seldom justify their actions and the resulting expenditure by adequate economic criteria. Too many executives do not a feel a true responsibility for the costs they create or the costs they protect by maintaining the status quo. A designer may take it granted that he has the privilege of creating any cost that may result from is design. He feels costs are the responsibility of the company or somebody else in the company. Proper reflection will make him conclude that costs that result from design are in his sphere of management and hence are his responsibility, because he and not somebody else selected the proposed design from all the possible alternative designs.

If an executive disregards the economic effects of a decision, he is disregarding the cost commitments that will result from his decision.

Engineering Efficiency Versus Financial Efficiency

In 1923, O.B. Goldman, who wrote the book, Financial Engineering,  said that the primary duty of the engineer is to consider costs in order to obtain real economy – to get the most power, for example, not from the least number of pounds of steam, but from the least possible number of dollars and cents: to get the best financial efficiency.”
The goal of equipment selection in a business system is acceptable financial efficiency, not engineering efficiency.

Searching for  Low Engineering Efficiency Alternatives

If the final choice is based on financial efficiency alone, the search for alternatives must be conducted on either side of current engineering efficiency. Search for higher financial efficiency is not necessarily a search for higher engineering efficiency.

Cost Reduction Expenditures and Income Expansion Expenditures

 Expenditure and Investment proposals can be for cost reduction or income expansion. In some cases, both may be realized.  A characteristic of cost reduction expenditure is that the decision does not affect the gross income. A decision in which the gross income increases is an income expansion proposal. For both the proposals, economic decision making is essential.  

Rate of Return on Capital (Finance)

Finance is the money resources of a business organization. Money resources of an organization consist of equity capital contributed by owners of the firm and loans (short-term as well as long-term) given by various  banks, other firms and individuals. All the entities who provide finance to a firm expect to get back the principal and additional return on principal. The business operations of a firm need have the ability to generate that return or more than that return to acquire capital or finance in the first place and then generate the return to satisfy the expectations afterward. This idea gives rise to cost of capital.

Cost of Capital

The user of capital must satisfy the profit motive of the supplier of capital. This obligation of the user of capital is termed as the cost for using capital or cost of capital. Hence all expenditure proposals need to include an evaluation mechanism that considers the cost of capital for the capital required to implement the proposal.

Profit: Accounting and Economics Viewpoints

Profits are measured by accountants. But they are evaluated by economists, engineering economists and financial executives.

The accountant computes profit earned during past periods after incomes and expenses are known. The accountant subtracts expenses from revenue to find the profit on the owner’s investment.
The economy analyst or engineering economy analyst tests the profitability of a proposed operation.

Engineering Economy Study

The process of engineering economy study will include data gathering and data analysis.
Analysis requires analytical methods and Engineering Economy texts mainly concentrated on analytical techniques. The analytical techniques express the alternatives in comparable measures of money with respect to their cost, revenue or return on capital.

Data gathering will include some current estimates made by engineers by combining the technical information and costs/prices relevant to the materials and processes used to provide goods or services. The data gathering effort cannot be a one time effort and systems are to be put in place to record appropriate data as and when it first appears. For this purpose accounting sections or departments (financial, cost and management accounting) and technical departments have to jointly work out the need for future engineering economy studies and instal appropriate recording systems.

Is There a Need for Engineer to Involve Themselves in Financial Calculations?

While the financial calculations that necessarily follow the engineers designs and technical estimates are in no sense an exclusive engineering function. Such calculations can be done by persons with accounting background and business administrators.

However, these calculations are such a necessary part of the numerous choices between technical alternatives that every engineer has to do as a part of his design function or process that an engineer who is not equipped to make them is a  poor choice for the job. A deficiency in this matter is particularly serious in an engineer who has administrative responsibility for technnical matters (Grant and Ireson, 1960).


George A. Taylor, Managerial and Engineering Economy, Van Nostrand Reinhold Company, New York, 1964.
Grant, Eugene, L., and W. Grant Ireson, Principles of Engineering Economy, 4th Ed., The Ronald Press Company, 1960, P.3.

Engineering Economics is an Efficiency Improvement Tool for Industrial Engineers

Engineering Economic Appraisal - A Special Role for Industrial Engineers

Engineering economic analysis is to be carried out by all engineers. These analysis reports must be appraised by IE department engineers. IEs can evaluate whether sufficient technical alternatives were considered in proposing the technical solution now recommended and then check the data and calculations of the economic analysis. From IE department, the proposal can go the project appraisal committee.

Engineering Economics is part of Industrial Engineering Tool Kit

Industrial Engineering Tool Kit


Engineering Economics - Knol Book by Narayana Rao

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Recently Published Books

Principles of Engineering Economic Analysis, 5th Edition
White, Case, Pratt
ISBN 978-0-470-11396-7, © 2010
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Originally posted in Knol

Updated on 2 December 2012

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