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Moral Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

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Page 1: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Moral Costs and Rational Choice: Theory and Experimental Evidence

James C. Cox, John A. List, Michael Price,

Vjollca Sadiraj, and Anya Samek

Page 2: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Dictator Games• Hundreds of dictator games in the past 30 years provide

evidence for altruism or warm glow• In standard dictator games

~60% of subjects pass positive amounts of money; allocating ~20% of endowment (Camerer, 2003)

• Changing the give vs. take action set produces some different results: Allowing taking significantly decreased transfers (List, 2007;

Bardsley, 2008) Take option effect is robust to heterogeneous adult subjects

with earned endowments (Cappelen, et al., 2013) Take vs. give option effect is robust to charitable contributions

(Grossman & Eckel, 2015) Recipients earn more in a take game than in a payoff

equivalent give game (Korenok, Millner & Razzolini, 2014)

Page 3: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Possible Interpretations• Not a “real behavioral phenomenon”; an effect of

an artificial environment such as:

“Hawthorn effect”?

“Experimenter demand effect”?

“Framing effect”?

Other artificial environment effect?

• Or maybe a Kitty Genovese effect?

Page 4: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Possible Interpretations (cont.)

• A “real behavioral phenomenon” that is:

Inconsistent with convex preference theory?

Inconsistent with rational choice theory?

Page 5: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Possible Interpretations (cont.)

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

−1 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Pe

rce

nta

ge

Amount Transferred

List (2007)

Baseline Take $1

Page 6: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Theoretical Interpretation of List (2007) Data

• In order for the data to be consistent with convex preference theory: The height of the blue bar at 0 must equal the

sum of the heights of the red bars at -1 and 0

The heights of the blue and red bars must be the same at all other transfer numbers

• In order for the data to be consistent with extant rational choice theory: No red bar to the right of -1 can be taller than the

corresponding blue bar

Page 7: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

List (2007), Bardsley (2008), Cappelen, et al. (2013)

• Data from these experiments are:

– Inconsistent with convex preference theory (including “social preferences” models)

– Almost completely consistent with extant rational choice theory

• These experiments:

– Stress-test convex preference theory

– Endowments and action sets are not well suited to stress-test rational choice theory

Page 8: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Outline of Contents

• Report an experimental design to stress-test rational choice theory

• Report an experiment with children• Review properties of conventional theory

– Convex preference theory (including “social preferences”)– Rational choice theory

• Develop a modified form of rational choice theory, with moral reference points, that explains:– Dependence on irrelevant alternatives (“contraction

effects”)– Dependence on give vs. take action sets (“framing

effects”)

• Use child experiment data and data from college student experiments to test alternative theories

Page 9: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Our Experiment

• 329 children, ages 3-7 (Average age: 5, min. 3.5; max. 7.4)

• Treatments include variations in:

– Action sets: Give, Take, Symmetric

– Initial endowments: Inequality, Equal, Envy

Page 10: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Treatments: Varying Endowments and Action Sets

• Compare Give, Take, Symmetric to investigate the effect of the action set on final outcomes.

• Across Inequality, Equal, Envy: compare the final allocation within action sets.

Page 11: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Feasible Budget Sets

• Give and Symmetric start at B• Take starts at A

Page 12: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Equal Treatments

Page 13: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Inequality Treatments

Page 14: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Envy Treatments

Page 15: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Randomization to Treatment• Between subjects: 3 – 4 year olds randomized

to Inequality, Equal, or Envy

• Within subjects: Plays each of Give, Take, Symmetric in random orderPayoff accumulates after each decision (PAS)

In the main text we report only the decision from the dictator game o when it is played first

o and the existence of the second and third choices is unknown to the child

Appendix D reports tests with all of the data

Page 16: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Average Allocations

Page 17: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Extant Rational Choice Theory

• The Chernoff (1954) contraction axiom (also known as Property α from Sen (1971) states:

Property α: if then

• In words, a most-preferred allocation from feasible set is also a most-preferred allocation in any contraction of the set that contains the allocation

G F F G G

F

G F

f

f

Page 18: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Explanation for Dictator Games

• For singleton choice sets: If , that is chosen from opportunity set , belongs to the subset then is chosen when the

the opportunity set is

• This means that no striped bar should be taller than corresponding bars in the intersection of feasible sets in the following figure

*

jQ

jQ

jQj j[A ,B ]

j j[A ,B ]

j j[A ,C ]

Page 19: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Explanation for Dictator Games

• For singleton choice sets: If , that is chosen from opportunity set , belongs to the subset then is chosen when the

the opportunity set is

• This means that no striped bar should be taller than corresponding bars in the intersection of feasible sets in the following figure

*

jQ

jQ

jQj j[A ,B ]

j j[A ,B ]

j j[A ,C ]

Page 20: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Example of Observed Contraction Effects

0%

10%

20%

30%

40%

50%

60%

70%

0 1 2 3 4 5 6 7 8 9 10 11 12

Per

centa

ge

Final Payoff to Dictator

Inequality

Give

Take

Symmetric

Page 21: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Introduction of Moral Reference Points

• We extend rational choice theory to include objectively-defined moral reference points.

• We here consider the N = 2 case needed for dictator games in the give vs. take literature:

– Let (m,y) denote an ordered pair of money payoffs for the dictator m = “my payoff” and the recipient y = “your payoff”

– Let denote the dictator’s compact feasible set

– Let and denote maximum feasible payoffs:

and

om

Foy

( ) sup{ | ( , ) }om F m m y F ( ) sup{ | ( , ) }oy F y m y F

Page 22: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Theory Generalization (cont.)

• The minimal expectations point M is:

and

• The moral reference point depends on M and the dictator's endowment:

• Any is consistent with contraction and action set effects. In the paper, we use the value

( ) sup{ | ( , ( )) }o

om F m m y F F ( ) sup{ | ( ( ), ) }o

oy F y m F y F

( ( ) (1 ) , ( ))r

o m of m F e y f

(0,1) 1/ 2

Page 23: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Graphical Depiction of Examplesy

10

6

6 10

2

2 4

AQ = Take Endowment

BQ = Give Endowment= Symmetric Endowment

CQ

m

Page 24: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Moral Monotonicity Axiom

• Let R denote “not smaller” or “not larger”

• For every agent i one has:

Moral Monotonicity Axiom (MMA):

If then , and gr r r r

i i i iG F g R f f

, gi if F G g R f G

Page 25: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Implications of MMA• MMA is a sufficient condition for the choice set to

satisfy contraction and expansion axioms (analogs of Sen’s properties and ) if opportunity sets preserve a moral reference point:

• Property : if and then

• Property : if and then

implies

M

M

G Fr rg f

F G G

G Fr rg f

G F G F

Page 26: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Testable Implications Within I, Q & E Treatments

• Let the choice point be t* when the action set is Take and the opportunity set is

• Let the choice point be g* when the action set is Give and the opportunity set is

• Let the choice point be s* when the action set is Symmetric and the opportunity set is

– And assume s*

• Contrasting implications:

Conventional rational choice theory implies: t* = g* = s*

Our theory implies: t* northwest g* northwest s*

j j[A ,B ]

j j[A ,B ]

j j[A ,C ]

j j[A ,B ]

Page 27: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Within Treatments Take vs. Give Effects

• Result 1: Effects on choices of within-treatment change from Give to Take action sets are weakly inconsistent with conventional rational choice theory but consistent with our model based on MMA.

Page 28: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Support for Result 1: Take vs. Give

Dependent Variable (1) (2) (3)

Dictator Payoff Inequality Equal Envy

Conditional mean estimates of

Give Action [+] 0.400* 0.246 1.174**

(0.216) (0.326) (0.458)

Observations 103 57a 46

Means {Take, Give}

Nobs {Take, Give}

{6.16, 6.51}

{50, 53}

{4.60, 5.06}

{25, 33}

{2.84, 3.38}

{25, 21}

(Kruskal-Wallis) Chi-Squared

2.51 3.26* 2.88*

Note: ademographics missing for one child. Predicted sign by MMA in square brackets. Standard errors in parentheses. Choice at the highest dictator’s payoff is

treated as hurdle. Includes Experimenter fixed effects and demographics (child age, race and gender). Take action set is the omitted category, and childrens’ choices

in the Symmetric action set are excluded from the analysis. ***p<0.01, ** p<0.05, * p<0.1

Table 3: Comparisons of Give vs. Take Action Sets

Average marginal effects from the Hurdle model (Cragg, 1971).

Page 29: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Within Treatments Contraction Effects

• Result 2: Effects on choices from within-treatment contractions of feasible sets are inconsistent with conventional rational choice theory but consistent with our model based on MMA.

Page 30: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Support for Result 2: Contraction

Dependent Variable

Dictator Payoff

(1)

Inequality

(2)

Equal

(3)

Envy

Give Action [-] -0.930*** -1.585*** -0.570

(0.263) (0.532) (0.482)

Take Action [-] -1.293*** -1.782*** -1.477***

(0.245) (0.522) (0.440)

Observations 143a 73a 64

Means (Take, Give, Symm.)

Nobs (Take, Give, Symm.)

(6.16, 6.51, 7.83)

(50, 53, 41)

(4.60, 5.06, 5.94)

(25, 33, 16)

(2.84, 3.38, 3.94)

(25, 21, 18)

(Kruskal-Wallis test)

Chi-Squared

52.07*** 15.51*** 12.25***

Note: MMA predicted sign in square brackets. Standard errors in parentheses. Includes Experimenter fixed effects and children demographics (gender, age,

race). The Symmetric action set is the omitted category. Only choices from [A, B] are included. Choice at the highest dictator’s payoff is treated as hurdle. ***

p<0.01, ** p<0.05, * p<0.1.

Table 4: Contraction of the Symmetric Set (within treatment)Average marginal effects from the hurdle model (Cragg, 1971).

Page 31: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Implications for Data from other Experiments

• Korenok, Millner & Razzolini (2014)– Their Contraction data are consistent with warm glow

model reported in Korenok, Millner & Razzolini (2013)

– Their Give vs. Take (“framing”) data are inconsistent with their theoretical model and Property alpha

– We show that their data are consistent with MMA

• Andreoni & Miller (2002)– They ask whether their data are consistent with GARP

– We show MMA places tighter restrictions on their data than does WARP

Page 32: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Give vs. Take Action Sets in Korenok, et al. (2014)

Page 33: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Action Sets in Korenok, et al. (cont.)

• Endowments are at points 1, 3, 6, 8, and 9

• Korenok, et al. theory and conventional rational choice theory imply choices invariant to these endowment (and give vs. take action set) changes

• The moral reference points for our theory are shown at points for j = 1, 3, 6, 8, and 9

• MMA implies that choice points move northwesterly along with endowments

jf

Page 34: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Implications of Data from Korenok, et al.

• The average recipient payoffs for the five scenarios are: S1($4.05), S3($5.01), S6($5.61), S8($6.59) and S9($6.31).

• The data are inconsistent with Korenok, et al. theory and with conventional rational choice theory

• The data support predictions of MMA except for the change from $6.59 to $6.31, which is insignificant

Page 35: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Some Feasible Sets from Andreoni & Miller

Recipient’s Payoffs

Dictator’s Payoffsfa fb

B

A

ba

Page 36: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

MMA and WARP

• Consider the WARP violation shown by choices A and B

• Note that the shaded quadrilateral (SQ) is a contraction of each budget set

• Looking at SQ as a contraction of the “steeper set”: – MMA (see Proposition 1) requires that A also be chosen from

SQ because the sets have the same moral reference point

• Looking at SQ as a contraction of the flatter set:– MMA requires that the choice from SQ is northwest of B

because is to the left of

• But this contradicts the choice of A from SQ

• Thus, any pair of choices of type A and B violate MMA

• MMA places tighter restrictions on the data than does WARP (in the figure, WARP implies B must be southeast of the intersection; MMA says it must be east of A)

af bf

Page 37: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Summary

• Data from List, Bardsley, and Cappelen, et al. contradict convex preference theory

• Data from our experiment and Korenok, et al. contradict

– Conventional rational choice theory

– Warm glow theory of Korenok, et al.

• Our theory with MMA is consistent with data

– From Take vs. Give

– From (“proper”) Contraction

Page 38: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Summary (cont.)

• Our theory with MMA is clearly testable, e.g.:

o It places tighter restrictions on data than does WARP in some dictator experiments

o It places restrictions across play in moonlighting and investment games

Page 39: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek
Page 40: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Making the Decision

“First, you and the other boy will get some stickers to start.”

“With the stickers on these plates, you still get to decide -- how many you want to keep, and how many you want the other boy to keep.”

Daniel’s box (Fixed endowment)“These are the stickers you definitely get to take home.”

Other boy’s box (Fixed endowment)“These are the stickers he definitely gets to take home.”

Daniel’s plate (Variable endowment) “Here are more stickers – they are yours now.”

Other boy’s plate (Variable endowment) “Here are even more stickers – they are his now.”

Page 41: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Fig. 5: Reference Points for Proper Contractions

Page 42: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Dependent Variable

Dictator Payoff

(1)

Symmetric Equal

Inequality Take/Give

(2)

Symmetric Envy

Inequality Take/Give

Give Action 0.082 1.301*** [+]

(0.277) (0.296)

Take Action -0.286 [-] 0.875*** [+]

(0.289) (0.320)

Observations 127 133

Means (Take, Give, Symm.)

Nobs (Take, Give, Symm.)

(6.16, 6.51, 6.42)

(50, 53, 24)

(6.16, 6.51, 5.37)

(50, 53, 30)

(Kruskal-Wallis test)

Chi-Squared 2.81 11.67***

Note: MMA predicted sign in square brackets. Standard errors in parentheses. Includes Experimenter fixed effects and children demographics (gender, age, race).

Table 5: Contraction of the Symmetric Set (across treatments)Average marginal effects from the hurdle model (Cragg, 1971).

Page 43: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Convex Preferences on Discrete Choice Sets

Page 44: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Strictly convex preferences on a discrete choice set

• The most preferred set is either a singleton or a set that contains two adjacent feasible points

• If Q* not in [Aj, Bj] is chosen from [Aj, Cj] then Bj will be chosen from [Aj, Bj] because:

o Bj is a convex combination of Q* (that belongs to

[Bj, Cj]) and X , for any given X in [Aj, Bj]

o Since Q* is preferred to X in [Aj, Cj], by strict convexity Bj is strictly preferred to X

Page 45: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Proof of Proposition 1

Page 46: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Proof of Properties

Let belong to both and . Consider any from As and have the same moral reference point,

MMA requires that These inequalities can be simultaneously satisfied if and only if ,

i.e. belongs to which concludes the proof for property

. Note, though, that any choice from must coincide with , an implication of which is must be a singleton. So, if the intersection of and is not empty then choices satisfy property .

and M M

f F G g .G

G F ,r rg f

and , .i i i ig f f g i

g f

f G

M g G

f G

GF

M

Page 47: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Both Axioms from Conventional Rational Choice Theory

Page 48: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Properties

• Samuelson (1938), Chernoff (1954), Arrow (1959), Sen (1971, 1986)

• Property : if then

A most-preferred allocation from feasible

set is also a most-preferred allocation in any contraction of the set that contains the allocation .

and

G F F G G

* *f F

F

G F*f

Page 49: Moral Costs and Rational Choice: Theory and … Costs and Rational Choice: Theory and Experimental Evidence James C. Cox, John A. List, Michael Price, Vjollca Sadiraj, and Anya Samek

Properties (cont.)

• For non-singleton choice sets one also has

• Property β: if and then

If the most-preferred set for feasible set contains at least one most-preferred point from the contraction set then it contains all of the most-preferred points of the contraction set.

• For finite sets, Properties α and β are necessary and sufficient conditions for a choice function to be rationalizable by a weak (complete & transitive) order (Sen, 1971)

G F G F G F *F F

G

and