Expected value is the weighted average value of the events for a probability distribution, i.e., it is the average value of the events that are expected to occur.. The standard deviation
Trang 1CHAPTER 24
DISCUSSION QUESTIONS
24-1
Q24-1 Before making a decision under conditions of
uncertainty, a manager should try to assess the
probabilities associated with alternative
possi-ble outcomes in order to determine the
proba-ble result of each alternative action Unless the
probabilities associated with possible outcomes
are determined, the effect of uncertainty cannot
be accounted for adequately, which may result
in inconsistent and unreliable decisions.
Q24-2 Expected value is the weighted average value
of the events for a probability distribution, i.e.,
it is the average value of the events that are
expected to occur.
Q24-3 The standard deviation of the expected value is
a measure of the variability of events within a
probability distribution and, as such, is viewed
as a measure of risk The larger the standard
deviation, the greater the risk that the actual
result will differ from the expected value.
Q24-4 The coefficient of variation relates the
stan-dard deviation for a probability distribution to
its expected value, thus allowing for
differ-ences in the relative size of different
probabil-ity distributions The coefficient of variation
provides a comparative measure of risk for
alternatives with different expected values.
Q24-5 A joint probability is the probability of the
simul-taneous occurrence of two or more events
(e.g., the probability of the occurrence of both
event A and event B, denoted as P(AB)),
whereas a conditional probability is the
proba-bility of the occurrence of one event given that
another event has occurred (e.g., the
probabili-ty of the occurrence of event A given that event
B has already occurred, denoted as P(AIB)) A
conditional probability implies that some
rela-tionship exists between the events.
Q24-6 Management should be interested in revising
probabilities as new information becomes
available, because new information may alter
the expected outcomes (i.e., probabilities)
enough to warrant making a different
deci-sion As a consequence, the revision of
prob-abilities may be necessary in order to provide
a basis for making the best decision.
Q24-7 Decision trees graphically portray alternatives
and their expected values and include a sequential decision dimension in the analysis They highlight decision points, alternatives, estimated results, related probabilities, and expected values They are especially useful in evaluating alternatives requiring sequential decisions that depend upon uncertain out- comes.
Q24-8 In a discrete probability distribution, the
possi-ble outcomes are limited to certain finite ues (e.g., 10, 11, 12, etc.) The number of shipments, orders, units of product, etc are events that could be described adequately by
val-a discrete probval-ability distribution For ience, the outcomes that occur in a discrete probability distribution are often limited to a fairly small number, but this need not neces- sarily be the case In contrast, the possible outcomes that may occur in a continuous probability distribution are infinite even within
conven-a limited rconven-ange Time, weight, volume, length, temperature, and economic value are exam- ples of continuous variables because they can take on an infinite number of values within a limited range (e.g., between 10 and
11 seconds times of 10.1 seconds, 10.53 onds, 10.926 seconds, etc could occur) Although such items are measured in discrete units, conceptually they can be subdivided into infinitely small units of measure (e.g., $2,
sec-$2.34, $2.627, $2.8935, etc.), and practically, the number of different discrete values an item may have without subdivision is large (e.g., the range of sales of $1 items between 10,000 and 20,000 units).
Q24-9 The normal distribution has the following
attractive properties:
(a) The normal distribution is symmetric and
it has only one mode This means that the expected value (which is the mean of the distribution) is equal to the most likely sin- gle event (the mode) Consequently, the single best guess is also the expected value.
Trang 2(b) The relationship between the portion of
the area under the curve for any given
interval from the mean, as measured in
standard deviations, is constant for all
nor-mal distributions This makes it possible to
determine the probability of the
occur-rence of an event within any interval if the
mean and standard deviation are known.
Q24-10 Monte Carlo simulation is used to obtain a
probabilistic approximation of the outcome
of a business system or problem that
con-tains numerous stochastic variables, but can
be modeled mathematically Its procedure
utilizes statistical sampling techniques and
is computer oriented.
Q24-11 A normal distribution is a symmetrical
distri-bution The expected value (the mean) and
the most likely event (the mode) are equal.
Since the most likely event would be used
even when the distribution of probable
out-comes is not considered specifically, and
since the most likely event and the expected
value are the same for a normal distribution,
the expected net present value would be the
same whether probability analysis is
incorpo-rated or not Nevertheless, probability
analy-sis should be incorporated into the capital
expenditure evaluation because it provides a
way for management to evaluate risk.
Q24-12 A mutiperiod problem expands the analysis
from a single variable to multiple variables
(i.e., the cash flows from each period are
treated as different random variables) As a
consequence, the expected net present value
of a capital expenditure proposal is treated as
a random variable drawn from a multivariate
probability distribution The variance for a
multivariate distribution is computed by
sum-ming the variances for each variable if the
variables are independent, or by summing
the standard deviations and squaring the total
if the variables are perfectly correlated
(squaring the total incorporates the
interac-tion between the dependent variables) To
consider the time value of money in a
mutiperiod capital expenditure proposal, the
periodic variances and the periodic standard
deviations should be discounted at the
com-pany’s weighted average cost of capital.
Q24-13 Cash flows are independent if the
magni-tude of cash flows in one period is not in any
way affected by the magnitude of cash flows
in another period Independent cash flows might be expected to occur when a capital expenditure relates to the production of an established product or service; the demand for which is expected to vary in response to temporary changes in consumer tastes and preferences or the capacity to purchase, which are uncorrelated between periods Q24-14 Cash flows are perfectly correlated if the mag-
nitude of cash flows in a subsequent period is dependent upon the magnitude of cash flows
in a preceding period Perfectly correlated cash flows might be expected to occur if a capital expenditure relates to the production of
a new product or the entrance of a product into a new market In such a case, consumer acceptance of the product in one period might
be expected to have a direct bearing an the level of sales in the following period.
Q24-15 If the periodic cash flows are neither
independent nor perfectly correlated, the variance of the net present value of a capital expenditure can be computed by (a) dividing the period cash flows into independent and dependent components; (b) computing the periodic variances for the independent cash flows and then discounting and summing to get the variance for the net present value of the independent cash flows; (c) computing the periodic variances for the dependent cash flows, taking the square root of each variance to get the periodic standard devia- tions, discounting and summing the periodic standard deviations, and squaring the total
to get the variance for the net present value
of the dependent cash flows; and (d) adding the variance for the net present value of the independent cash flows to the variance of the net present value of the dependent cash flows.
Q24-16 MADM stands for multi-attribute decision
model, and it is an expenditure evaluation tool that explicitly incorporates both quanti- tative and nonquantitative factors into the decision analysis Traditional economic eval- uation tools do not incorporate qualitative factors into the decision model, yet most of the benefits to be derived from investments
in new technologies are strategic and cult to quantify MADM attempts to remedy this problem by giving weight to noneco- nomic variables.
Trang 3Volume Value Probability Value
Trang 4E24-2
Trang 5Cost to purchase thermocouplers:
Units needed annually (18,000 ÷ (1 – 10)) 20,000 Unit cost × $15 Total estimated cost if thermocouplers purchased $300,000 Weighted average unit cost (expected value) to manufacture thermocouplers:
Manufacturing yields an estimated savings of $26,300 ($300,000 – $273,700), subject to the accuracy of estimated data If data are accurate, manufacturing appears desirable; assuming that the savings represents an acceptable rate of return on additional invested capital, there is no better alternative use of limited available facilities and equipment, and quality and production schedule demands can be met.
Trang 6Table of expected values of possible strategies (000s omitted):
Expected Purchases/Sales 100 120 140 180 Value
Trang 7(2) The expected value of perfect information is the difference between the average
contribution margin using the best strategy (ordering 30,000 hot dogs) and the probabilities and average contribution margin if Wurst knew in advance what the sales level would be each Saturday.
Average contribution margin if Wurst knew sales level:
$2,000 × 1 $ 200
$4,000 × 2 800
$6,000 × 4 2,400
$8,000 × 3 2,400 $5,800 Average contribution margin using expected value
Contribution margin improved by $1,800
Since the contribution margin would be improved by $1,800, Wurst could afford
to pay up to $1,800 for “perfect” information.
E24-6
Prior Probability × Conditional Posterior
Trang 8Since the expected value of not moving exceeds that of moving, the manager should not move the stereo store to the shopping mall ($42,000 > 40,000).
CGA-Canada (adapted) Reprint with permission.
Market demand increases (.3)
Market demand increases (.3) Market demand remains same (.5)
Market demand remains same (.5) Market demand declines (.2)
Market demand declines (.2)
$ 30,000
25,000
–5,000
$ 50,000 –10,000
Trang 9The firm should make the sub-assembly rather than buy it because the expected value of making the sub-assembly is $26,000, which is greater than the expected value of buying ($24,500).
CGA-Canada (adapted) Reprint with permission.
High demand (.4)
High demand (.4) Medium demand (.3)
Medium demand (.3) Low demand (.3)
Expected Value
Trang 101 $300,000 expected profit – $10,000 cost of applying for rezoning.
2 $100,000 expected profit – $10,000 cost of applying for rezoning.
The land developer should bid on parcel B, and, if successful, apply for rezoning because the expected value of this alternative is greater than any other.
CGA-Canada (adapted) Reprint with permission.
Successful (.6)
Successful (.5) Unsuccessful (.4)
Unsuccessful (.5)
Unsuccessful (.2)
Apply
for Rezoning
Expected Value
for Rez oning
Trang 11Expected net present value $ 1,775*
*The difference in the results is due to rounding in the present value tables.
σσ = 7 496 , units
Trang 12Present
Standard deviation of NPV $3,791*
*The difference in the results is due to rounding in the present value tables.
Trang 13Standard Deviation of NPV for
dependent cash flows $6,846.00
Variance of NPV for dependent cash flows = ($6,846) 2 = $46,867,716
Variance of NPV for independent cash flows $ 3,126,940
Variance of NPV for dependent cash flows 46,867,716
Variance of total NPV of investment $49,994,656
Trang 14(1) The 95% confidence interval for the net present value is a range between a low
of –$20,000 ($30,000 expected NPV – (2 × $25,000 standard deviation)) and a high
of $80,000 ($30,000 expected NPV + (2 × $25,000 standard deviation)).
(2) There is a 88493 probability that the NPV of the investment will be positive, i.e.,
the 5 area above the mean plus the 38493 area below the mean (determined from the table of Z values in Exhibit 24-8 of the text for ( µµ – x) ÷ σσ = ($30,000
expected NPV – 0) ÷ $25,000 = 1.20 σσ).
Trang 15Direct materials (60,000 units × $25) $1,500,000 Direct labor (60,000 units × $8.80 per
hour most likely rate × 2 hours) 1,056,000 Variable overhead (60,000 units ×
($.40 supplies + $.35 materials handling + $1.25 heat, light, and power)
× 2 hours) 240,000 Promotion fee (60,000 units × $6) 360,000 3,156,000 Contribution margin $2,844,000 Additional fixed costs:
Supervisor salary $ 28,000 Equipment lease rentals 150,000 178,000 Annual pretax advantage of introducing new
product $2,666,000
(2) Expected value approach:
Sales in Units Probability Expected Value 50,000 25 12,500
Trang 16Supervisor salary $ 28,000 Equipment lease rentals 150,000 178,000 Expected annual pretax advantage $2,743,250
(3) In this situation, Monte Carlo simulation could be used A linear equation for the
net advantage would have to be developed that included the two variable items (sales volume and hourly direct labor costs) treated as independent stochastic variables The probability distributions for sales volume and hourly direct labor cost would be simulated and pairs of values would be selected for entry into the equation, using a random number generator The net pretax advantage would be calculated and recorded, and then a new set of values for the stochastic vari- ables would be determined and reentered into the equation A large number of iterations would be calculated and recorded to determine the approximate distribution of the net pretax advantage The distribution would have a calculat-
ed mean (which would be interpreted as the expected annual net pretax tage) and a standard deviation (which could be interpreted as a measure of the product’s risk).
Trang 17Plan 2
Urban service calls (850 calls × 60% urban × $450 per call) $229,500 Rural service calls (850 calls × 40% rural × $350 per call) 119,000 Parts ($60 expected value per call × 850 calls) 51,000 Estimated total cost of Plan 2 $399,500
Plan 3
Employee salaries (9 employees × $24,000 average salary) $216,000 Employee fringe benefits ($216,000 employee wages × 35%) 75,600 Preventive maintenance parts (200 calls per employee ×
9 employees × $15 in parts per call) 27,000 Repair parts ((850 calls × (1 – 30%)) ×
($60 expected value per call × (1 – 20%))) 28,560 Estimated total cost of Plan 3 $347,160
Trang 18Rejected During Assembly Rejected During Performance Testing
Hourly cost to = Direct labor + Variable overhead
Maximum amount Cost of rejections Cost of rejections
Number for quality = during assembly + during performance ×
of lots
= ($140 + $300) × (1,000,000 units ÷ 1,000 units per lot)
= $440,000
(
(
( (
Trang 19(1) The payoff table of expected contribution margins for Kenton Clothiers’ shirt
order sizes follows:
Possible Actions Contribution Margin (Conditional Value) Contribution Margin
* 100 shirts at the regular $30 sales price × $7 CM per shirt = $700 CM
** (100 shirts at the regular $30 sales price × $8 CM per shirt) – (100 shirts at the
$15 reduced price × $7 loss per shirt) = $100 CM
*** (.12 probability × $(500)) + (.48 probability × $1,000) + (.36 probability × $2,500) + (.04 probability × $4,000) = $1,480 CM
(2) The best strategy for Kenton Clothiers would be to order 300 shirts each year
because it would result in the largest contribution margin over time The cient of variation for the best strategy (i.e., purchasing 300 shirts each year) is 615 determined as follows:
E
996 795
of variation