1. AGEC 608 Lecture 06, p. 1 AGEC 608: Lecture 6 Objective: Outline approach for discounting benefits and costs that accrue at different points in time Readings: –Boardman, Chapter 6 Homework #2: Chapter 3, problem 1 Chapter 3, problem 2 Chapter 4, problem 3 due: March 13 Homework #3: Chapter 4, problem 2 Chapter 5, problem 1 Chapter 6, problem 4 due: March 27

2. AGEC 608 Lecture 06, p. 2 BCA in a timeless world Dam construction Costs: Materials = $500,000 Labor = $600,000 Total Cost = $1,100,000

3. AGEC 608 Lecture 06, p. 3 BCA in a timeless world Dam construction Benefits: Recreation = $400,000 Flood control = $300,000 Electricity = $500,000 Total Benefit =$1,200,000

4. AGEC 608 Lecture 06, p. 4 BCA in a timeless world Dam construction Total Benefit =$1,200,000 Total Cost = 1,100,000 Net Benefit = 100,000 Benefit exceeds cost, so dam appears to be a good investment

5. AGEC 608 Lecture 06, p. 5 Undiscounted Measures of Project Worth Ranking by inspection – –Sometimes it is possible to ascertain whether a project is worthwhile simply by looking at the flows, or to compare candidate projects. Payback period –Defined as the length of time from the beginning of the project until the net returns equals the value of the initial investment.

6. AGEC 608 Lecture 06, p. 6 Undiscounted Measures of Project Worth Proceeds per unit of outlay –Total net value of the incremental output divided by the total investment. Average annual proceeds per unit of outlay –Compute total net value of incremental output, divide this by the number of years of production, and then divide the resulting figure by the capital investment. Average income on book value of investment –Ratio of the average income to the book value of assets (the value after subtracting depreciation) stated in percentage terms.

7. AGEC 608 Lecture 06, p. 7 Time and Discounting Often the benefits and costs of a project accrue at different times. The technique used to deal with this issue is discounting.

8. AGEC 608 Lecture 06, p. 8 Discounting Discounting is a technique used to convert all benefits and costs to a common point in time, usually the present. The value of a project, expressed in terms of the present, is called the Present Value.

9. AGEC 608 Lecture 06, p. 9 Discounting Discounting is based on the premise that a dollar of benefit received today is worth more than a dollar of benefit received in the future. The bias arises because current resources can be invested. Discounting is the opposite of compounding.

10. AGEC 608 Lecture 06, p. 10 Discounting The rate at which a current value is compounded is called the interest rate. The rate at which a future value is discounted is called the discount rate.

11. AGEC 608 Lecture 06, p. 11 Interest Formulas 1) Present value of a variable time stream a) Discrete end of year: b) Discrete mid-year: c) Continuous:

12. AGEC 608 Lecture 06, p. 12 Interest Formulas 2) Compound interest a) Discrete annual compounding: b) Discrete monthly compounding: c) Continuous compounding:

13. AGEC 608 Lecture 06, p. 13 Interest Formulas 3) Annuity whose present value is PV (capital recovery factor): As t approaches infinity, this formula becomes

14. AGEC 608 Lecture 06, p. 14 Computing a present value PV = P t / (1 + r) t PV = present value P t = value at time t r = interest (discount) rate t = year in which P t is realized

15. AGEC 608 Lecture 06, p. 15 BCA with discounting Dam revisited Total Benefits accrue when dam is finished (t = 1) Total Costs accrue at start of construction (t = 0) Discount rate = 10% Should the dam be built?

16. AGEC 608 Lecture 06, p. 16 Total Benefits accrue when dam is finished (t = 1), so P t = $1,200,000 and PV of benefit is: $1,200,000 / (1+0.10) 1 = $1,090,909 Total Costs accrue at start of construction (t = 0), so P t = $1,100,000 and PV of benefit is: $1,100,000 / (1+0.10) 0 = $1,100,000 PV(B) < PV(C) The dam should not be built. Dam construction revisited

17. AGEC 608 Lecture 06, p. 17 Total Benefits accrue in the future (i.e. when dam is finished). The process of discounting reduces the value of those benefits because they occur in the future. Why the reversal? Because the merit of a project can hinge on the choice of discount rate, it can be a source of debate. There is no simple rule for choosing a discount rate. Often a “well known” interest rate is used.

18. AGEC 608 Lecture 06, p. 18 Discounted Measures of Project Worth 1) Net present value (NPV) 2) Internal rate of return - the rate of interest that equates NPV to 0. Acceptance criterion: NPV > 0 Acceptance criterion: IRR > social discount rate

19. AGEC 608 Lecture 06, p. 19 Discounted Measures of Project Worth 3)Benefit-cost ratio The ratio of discounted benefits to discounted costs Acceptance criterion: