consistent framing
DESCRIPTION
Consistent framing. Notes for chapter 8. Accounting and decisions. In accounting decision problems are often modified Fixed costs are not included Often only incremental costs are considered Costs are approximated Profit maximization is often assumed Cost minimization - PowerPoint PPT PresentationTRANSCRIPT
1
Consistent framing
Notes for chapter 8
2
Accounting and decisions• In accounting decision problems are often modified
Fixed costs are not included– Often only incremental costs are considered– Costs are approximated
• Profit maximization is often assumed– Cost minimization
• Uncertainty is often not considered– Risk and risk premiums– Variance and covariance among projects
• Time preferences are also disregarded– No discounting
3
More accounting
• Product classification– Primary product – Secondary products– Scrap
• Cost allocations• Transfer pricing• ABC costing
4
Rational Behavior
• Intelligent, wise, and enlightened.• Economic setting pursue
– Self-interest – Wealth
• How do we describe rationality• How do we model rationality
5
Rational Behavior
• Consistency– Complete and transitive ranking
• Two statements equivalent. – Ranking complete and transitive. – Exists a function on A, ω(a),
• a`, a ́ A, ω(a`) ≥ ω(a ́) ∈• Only when a` is ranked as good as a ́. • (The set A is finite)
• Smoothness
6
A generic decision problem
max ( )subject to
aa A
We want to maximize a generic function subject to some constraints of feasibility.This could take the form as:
7
Decision with two variables
8
Irrelevance of Increasing Transformations
21
22 1
2 2 23 1
4 2 1
graph 1: ( ) 10 20
graph 2 : ( ) ( ) 20 10
graph 3: ( ) 1 [ ( )] 1 [10 20]
graph 4 : ( ) ln[ ( )] ln[ ( ) 20]
a a a
a a a a
a a a a
a a a
9
Irrelevance of Increasing Transformations
10
Irrelevance of Increasing Transformations
11
Irrelevance of Increasing Transformations
• Definition 19 Function T is an increasing transformation of function ω(a) if ω (a) > ω (â) if and only if T[ω(a)] > T[ω(â)] for every a and â in the domain of the original function
• The solution to a decision problem is unaffected by an increasing transformation of the objective function.
12
Shadow prices
max(40 42 ) (30 30 ) max10 12400
2 500
x y x y x yx yx y
(300,100)
13
Local search - Shadow prices
0, 0max ( , ) 10 12
subject to 8
2 12
x yx y x y
x y
x y
Optimal choice is x = 4, y = 4
14
Component searches are possibleInteractions
0, 0max ( , ) 10 12
subject to 8
2 12
x yx y x y
x y
x y
First constraint8
Second constrainty 0.5(12-x)
y x
15
Component searches are possible
( ) min{8 ;.5(12 )}y g x x x
ˆ( , ( )) ( ) 10 12 min{8 ;.5(12 )}10 6(12 ) 72 4 , 0 410 12(8 ) 96 2 , 4 8
w x g x x x x xx x x if xx x x if x
This reduces to:
Then we get:
16
Component searches are possibleInteractions
17
Component searches are possible
1 21 2 1 20, 0
1 2
1
( ; ) min ( , ) 5 20
subject to15
z zC q P z z z z
q z zz
2
21
qzz
1
2
1 101
1
ˆ( ; ) min ( ) 5 20
subject to 15z
qC q P z zz
z
18
Component searches are possible
,max ( , )
x X y Yx y
max{max ( , )}x X y Y
x y
ˆmax{max ( , )} max ( , ( )) max ( )x X y Y x X x X
x y x g x x
19
Component search
• When faced with an optimization problem of several variables we do component search when we solve the problem sequentially, by first optimizing with respect to one variable then the next etc.
20
( ) min{400 ;.5(500 )}10 12 ( ) 10 12min{400 ;.5(500 )}
3000 4 0 3004200 2 300 400
0 400
y g x x xx g x x x x
x xx x
x
21
22
23
24
Consistent Framing
• 3 principles:– Irrelevance of Increasing Transformation– Local searches are possible– Component searches are Possible
25
26
27
28
29
30
31
Application of framing principles and cost functions
32
New framing!
33
Yet another framing!
2 1 1 1( ) min{8 ;.5(12 )}q g q q q
1 1 1 1 1
1 1 1 1
1 1 1 1
ˆ( , ( )) ( ) 10 12 min{8 ;.5(12 )}10 6(12 ) 72 4 , 0 410 12(8 ) 96 2 , 4 8
w x g q q q q qq q q if qq q q if q
Using Component search this reduces to:
Then we get:
34
Cost function I
Product 1 Product 2
Direct laborDirect materialVariable overhead
203030
404060
Variable product cost 80 140
1 2 1 2 1 2 1 2 1 2( , ) 20( 2 ) 10(3 4 ) 15(2 4 ) 80 14050000 1.5
C q q q q q q q q q qOV DL
35
Cost function II
Direct laborDirect materialVariable overheadExternality
203030
6
20303012
Variable product cost 86 92
1 1 1
1 1 1
( ) (80 6) 72 0 4( ) (80 12) 96 4 8
C q q qC q q q
10 4q 14 8q
36
Cost function III
Frame Explicit choices
Implicit choices
Marginal cost of first
productI q1,q2,
z1,z2,z3
N/A N/A
II q1,q2 z1,z2,z3 80
III q1 q2,z1,z2,z3 86 or 92
37
Changed parameters
1 2 1 2 3
1 2
1 2
1 1 2
2 1 2
3 1 2
* * * * *1 2 1 2 3
1 2 3 4 5
1 2
max 90 152149 20 10 15. .
82 12
23 42 4
Optimal solution: 8; 0; 8; 24; 16Dual variables: 10, 0, 20, 10, 15.Cost function: ( , ) 8
q q z z zs tq qq qz q qz q qz q q
q q z z z
C q q
1 20 140q q
38
Cost function –Changed parameters
Frame Explicit choices
Implicit choices
Marginal cost of first
productI q1,q2,
z1,z2,z3
N/A N/A
II q1,q2 z1,z2,z3 80
III q1 q2,z1,z2,z3 80
39
Frame I – Short Term
40
Frame II – Short Term
1 2 2 3
1 2 1 2 1 2
1 2
1 2
1 2
1 2
1 2
90 149 10 1590 149 10(3 4 ) 15(2 4 )(90 30 30) (149 40 60)(90 60) (149 100)
max 30 49.
82 8
q q z zq q q q q q
q qq q
orq q
stq qq q
41
Frame II – Short Term
• Short run cost: C(q1,q2)=60q1 +100q2
• No labor cost• New use of the accounting library• What we mean by cost – depends!
Product 1 Product 2
Direct laborDirect materialVariable overhead
03030
04060
Variable product cost 60 100
42
Cost terminology
• Cost and benefit• F(z) = B(z) – C(z)
– Separation always possible– Separation hardly unique
• Relevant cost– Is simply the portion of the cost function that
varies with the options at hand– Depends upon framing
43
Our objective
• Are we maximizing profit?• Are we maximizing wealth?• Are we maximizing utility?
– Are these different?• What happened to uncertainty?• How do we cope with uncertainty?• Is risk aversion part of our story?
44
Back to accounting• Cost function
– Which products are included?– How is scrap accounted for?
• Cost allocation– Are externalities accounted for?
• Transfer pricing– Linear pricing – first order condition maintained?
• ABC costing– Approximation of cost function?
45
Conclusions • Ease of analysis vs complete specification• Framing is this decision• Notion of cost follows frame• Cost allocation might be part of framing• Where did the problem set-up come from
– Out of the blue– A handy and clever representation of the problem at
hand• Professional judgment