Perfectly Specified Decision Process, Cont.

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Transcript Perfectly Specified Decision Process, Cont.

Chapter 3 The Decision Usefulness Approach to Financial Reporting

© 2006 Pearson Education Canada Inc.

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Single-Person Decision Theory

Perfectly Specified Decision Process

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Motivation for Decision Theory Model

A

model of rational decision making in the face of uncertainty

Other ways to make decisions?Captures

average investor behaviour?

Helps us understand how financial

statement information is useful

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Example

Perfectly Specified Decision ProcessA game against

Nature . “Nature does not think”

NB: Concept of an “

Information System ”

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Perfectly Specified Decision Process Consider an investor with $10,000 to invest in one of the following mutually exclusive acts: a 1 : buy shares of x Ltd. For $10,000 a 2 : buy Canada Savings Bonds (CSB) for $10,000 Let there be 3 “states of nature”: θ 1 : shares fall 10% in market value θ 2 : shares hold steady θ 3 : shares rise 80%

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Perfectly Specified Decision Process, Cont.

Prior Payoff Table Probabilities Outcome θ 1 θ 2 a 1 a 2 -1000 1000 0 1000 θ 3 8000 1000 P( θ 1 ) = .05

P(θ 2 ) = .70

P(θ 3 ) = .25

1.00

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Perfectly Specified Decision Process, Cont.

Assume the investor uses expected monetary value as a decision criterion (EMV) EMV (a 1 ): (.05)(-1000) + 0 + .25(8000) = 1950 EMV (a 2 ): (.05)(1000) + .70(-1000) +.25 (1000) = 1000 Therefore, if investor acts now, should take a 1 .

But: May be worthwhile to secure additional information.

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Decision Problem

Think of the financial statements of X Ltd. as an information system conveying information about probabilities of θ.

Assume the financial statements will give one of the following 3 mutually exclusive messages:

m

1 :"

poor

"  

NI CA

/ /

SE CL

  .

05 1 .

9

m

2 :"

fair

"   

NI CA

/ /

SE CL

  .

12 2 .

0

m

3 :"

good

"

NI

/

SE CA

/

CL

 .

18  2 .

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Decision Problem, Cont.

The information system can be characterized by the following table: θ 1 Θ 2 θ 3 P(m 1 /θ) .75

.50

.10

P(m 2 /θ) .20

.30

.20

P(m 3 /θ) .05

.20

.70

These conditional probabilities, or likelihoods, are the probabilities of receiving the various messages conditional on each state being true.

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Decision Problem, Cont.

Now, for any message, the decision maker can revise his/her prior probabilities using

Bayes’ Theorem.

Suppose that

m

1 statements.

was received from the financial Then:

P

  1 /

m

1   

P

   

P

1 

m

1 /

m

1  /

P

 1    (.

05 )(.

75 ) .

4125  .

09 Similarly:

P

(  2 /

m

1 ) =P(

m

1 ) =.85

P

(  3 /

m

1 ) =.06

1.00

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Decision Problem, Cont.

Note the EMV of each act is

EMV

(

a

1 )  (.

09 )(  1000 ) 

EMV

(

a

2 )  1000 0  (.

06 )( 8000 )  $ 390 So if

m

1 were received act a 2 would be chosen.

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Decision Problem, Cont.

You should verify that if

m

2 was received:

P

(  1

P

(  2

P

(  3 /

m

2 ) /

m

2 ) /

m

2 )  .

0370  .

7778  .

1852 where

P

(

m

2 )   

P

(

m

2  .

2700 /  )

P

(  ) 1 .

0000 And the optional act is then

a

1 with EMV of $1444.48.

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Decision Problem, Cont.

Similarly, if

m

3 was received:

P

(  1

P

(  2

P

(  3 /

m

3 ) /

m

3 ) /

m

3 )  .

0079  .

4409  .

5512 1 .

0000 where

P

(

m

3 )  .

3175 © 2006 Pearson Education Canada Inc.

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The Information System

One of the Most Important Text

Concepts

Conditional on Each State of Nature (i.e.,

future firm performance), gives Probability of the GN or BN in the Financial Statements Objective

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The Information System, Cont’d.

Translation of First Entry in Information

System Example in Table 3.2 of Text:

If future firm performance is going to be good, the probability that the current financial statements will show GN is 0.80

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Information Defined

Information is Evidence that has the

Potential to Affect an Individual’s Decision

An

ex ante definition

Individuals receive information all the timeIndividual-specificAre financial statements information? © 2006 Pearson Education Canada Inc.

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Does it Work?

Problems of Implementing ModelSpecify states of naturePrior probabilities of states (subjective)PayoffsInformation system s/b objectiveForces Careful ConsiderationHow Else to Decide?Captures

Average Behaviour

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The Rational Investor

DefinitionMaximizes expected utility, using the single-

person decision theory model

May be risk averseThen, will diversifyNeeds information about risk as well as expected

return

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Beta

DefinitionStandardized covariance between return on

share and return on market

Only Relevant Risk Measure for a

Reasonably Diversified Investor

Why? Because firm specific risk diversifies

away.

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Decision Theory Model Underlies Concepts Statements

Rationale for Concepts StatementsExamplesFASB SFAC No. 1FASB SFAC No. 2

CICA Handbook , Section 1000

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