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AUTHOR'S PROOF<br />

Metadata of the article that will be visualized in OnlineFirst<br />

_____________________________________________________________________________________<br />

Please note: Images will appear in color online but will be printed in black and white.<br />

_____________________________________________________________________________________<br />

1 Article Title Reference distributions and inequality measurement<br />

2 Article Sub-Title<br />

3 Article Copyright -<br />

Year<br />

Springer Science+Business Media New York 2013<br />

(This will be the copyright line in the final PDF)<br />

4 Journal Name The Journal of Economic Inequality<br />

5<br />

Family Name<br />

6 Particle<br />

Flachaire<br />

7 Given Name Emmanuel<br />

8 Corresponding Suffix<br />

9 Author<br />

Organization Aix-Marseille Université<br />

10 Division Greqam<br />

11 Address 2 rue de la Charité, 13002, Marseille, France<br />

12 e-mail emmanuel.flachaire@univ-cezanne.fr<br />

13<br />

Family Name<br />

14 Particle<br />

Cowell<br />

15 Given Name Frank A.<br />

16 Suffix<br />

Author<br />

17 Organization London School of Economics<br />

18 Division Sticerd<br />

19 Address Houghton Street, London, WC2A 2AE, UK<br />

20 e-mail None<br />

21<br />

Family Name<br />

22 Particle<br />

Bandyopadhyay<br />

23 Given Name Sanghamitra<br />

24 Suffix<br />

Author<br />

25 Organization University of London<br />

26 Division Queen Mary<br />

27 Address Mile End Road, London, E1 4NS, UK<br />

28 e-mail None<br />

29<br />

30 Schedule Revised<br />

Received 3 May 2011<br />

31 Accepted 7 December 2012


AUTHOR'S PROOF<br />

32 Abstract We investigate a general problem of comparing pairs of distribution<br />

which includes approaches to inequality measurement, the<br />

evaluation of “unfair” income inequality, evaluation of inequality<br />

relative to norm incomes, and goodness of fit. We show how to<br />

represent the generic problem simply using (1) a class of<br />

divergence measures derived from a parsimonious set of axioms<br />

and (2) alternative types of “reference distributions.” The problems<br />

of appropriate statistical implementation are discussed and<br />

empirical illustrations of the technique are provided using a variety<br />

of reference distributions.<br />

33 Keywords<br />

separated by ' - '<br />

34 Foot note<br />

information<br />

Divergence measures - Generalised entropy measures - Income<br />

distribution - Inequality measurement - D63 - C10


AUTHOR'S PROOF<br />

J Econ Inequal<br />

DOI 10.1007/s10888-012-9238-z<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

Reference distributions and inequality measurement<br />

Frank A. Cowell · Emmanuel Flachaire ·<br />

Sanghamitra Bandyopadhyay<br />

Received: 3 May 2011 / Accepted: 7 December 2012<br />

© Springer Science+Business Media New York 2013<br />

Abstract We investigate a general problem of comparing pairs of distribution which 1<br />

includes approaches to inequality measurement, the evaluation of “unfair” income 2<br />

inequality, evaluation of inequality relative to norm incomes, and goodness of fit. 3<br />

We show how to represent the generic problem simply using (1) a class of divergence 4<br />

measures derived from a parsimonious set of axioms and (2) alternative types of 5<br />

“reference distributions.” The problems of appropriate statistical implementation 6<br />

are discussed and empirical illustrations of the technique are provided using a variety 7<br />

of reference distributions. 8<br />

Keywords Divergence measures · Generalised entropy measures · 9<br />

Income distribution · Inequality measurement 10<br />

JEL Classification D63 · C10 11<br />

1 Introduction 12<br />

UNCORRECTED PROOF<br />

There is a broad class of problems in distributional analysis that involve comparing 13<br />

two distributions. This may involve judging whether a functional form is a good 14<br />

fit to an empirical distribution; it may involve computation of the divergence of 15<br />

F. A. Cowell Q1<br />

Sticerd, London School of Economics, Houghton Street, London WC2A 2AE, UK<br />

E. Flachaire (B)<br />

Greqam, Aix-Marseille Université, 2 rue de la Charité 13002 Marseille, France<br />

e-mail: emmanuel.flachaire@univ-cezanne.fr<br />

S. Bandyopadhyay<br />

Queen Mary, University of London, Mile End Road, London E1 4NS, UK


AUTHOR'S PROOF<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

F. A. Cowell et al.<br />

16<br />

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49<br />

an empirical distribution from a theoretical economic model; it may involve the<br />

ethical evaluation of an empirical distribution with reference to some norm or ideal<br />

distribution. This paper shows how the class of problems can be characterised in a<br />

way that has a natural interpretation in terms of familiar analytical tools.<br />

This is not some recondite or abstruse topic. Several authors have explicitly<br />

characterised inequality using this two-distribution paradigm: an inequality measure<br />

is defined in terms of the divergence of an empirical income distribution from<br />

an equitable reference distribution [5, 20, 28]. Furthermore several recent papers<br />

have revived interest in the idea of inequality evaluations with reference to “norm<br />

incomes” or a reference distribution; 1 in particular some authors have focused on<br />

replacing a perfectly egalitarian reference distribution with one that takes explicit<br />

account of fairness [3, 19]. In recent contributions Magdalou and Nock [27] have also<br />

examined the concept of divergence between any two income distributions and its<br />

economic interpretation and Cowell et al. [8] show how similar concepts can be used<br />

to formulate an approach to the measurement of goodness of fit. 2<br />

In this paper we use an aprioriapproach to the problem that allows one to<br />

construct a distance concept that is appropriate for characterising the divergence<br />

between the empirical distribution function and a proposed reference distribution.<br />

The approach is related to results in information theory and is adaptable to other<br />

fields in economics that make use of models of distributions [10]. The paper is<br />

structured as follows. Section 2 introduces the concept of divergence and a set of<br />

principles for distributional comparisons in terms of divergence; we show how these<br />

principles characterise a class of measures and discuss different concepts of reference<br />

distribution that are relevant for different versions of the generic problem under<br />

consideration. Section 3 discusses issues of implementation and Section 4 performs<br />

a set of experiments and applications using the proposed measures and UK income<br />

data. Section 5 concludes.<br />

2 The approach<br />

The essence of the problem is the characterisation of the divergence of an income<br />

distribution from a reference distribution: this divergence can be seen as an aggregation<br />

of discrepancies in different parts of the distribution. To fix ideas we<br />

may interpret this in terms of a classic modelling problem: comparing an Empirical<br />

Distribution Function (EDF) ˆF (x) = 1 ∑ n<br />

n+1 i=1 ι (x i ≤ x) 3 and a theoretical reference<br />

distribution F ∗ . For instance, Fig. 1 presents an EDF (dotted line) and a theoretical<br />

UNCORRECTED PROOF<br />

1 Almås et al. [4] compare “actual and equalizing earnings”; their work is related to Paglin’s Gini [29]<br />

and Wertz’s Gini [32]. Also see Jenkins and O’Higgins [25] and Garvy [24].<br />

2 The Cowell et al. [8] approach differs from that developed here in that it deals with the problem of<br />

continuous reference distributions on unbounded support.<br />

3 ι is an indicator function such that ι (S) = 1 if statement S is true and ι (S) = 0 otherwise. We use 1<br />

n+1<br />

rather than 1 n to avoid a problem where i = n. Had we used i n in Eq. 1 then y n would automatically<br />

be set to sup (X) where X is the support of F ∗ .


AUTHOR'S PROOF<br />

Reference distributions and inequality measurement<br />

Fig. 1 Quantile approach<br />

x<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

Q2<br />

Q3<br />

°<br />

°<br />

°<br />

°<br />

Δ x 3<br />

°<br />

x 3 F −1 *<br />

(·)<br />

1<br />

reference distribution (solid line) on a reverse graph, with q denoting proportions 50<br />

of the population on the horizontal axis and the income quantiles on the vertical 51<br />

axis. There are two obvious ways to describe discrepancies between the EDF and the 52<br />

reference distribution: 53<br />

1. The standard approach in the goodness-of-fit literature is based on the “horizon- 54<br />

tal” differences between ˆF (x) and F ∗ (x) for any given x. 55<br />

2. An alternative approach is to compare, for given q values, the corresponding q- 56<br />

quantiles given by the EDF and F ∗ . Denote by {x (1) , x (2) , ..., x (n) } the members 57<br />

of the sample in increasing order; the corresponding values given by the EDF 58<br />

are the adjusted sample proportion q ={ 1<br />

n+1 , 2<br />

n+1 ,..., n<br />

} and, for each q, the 59<br />

n+1<br />

corresponding value for the reference distribution is equal to 60<br />

UNCORRECTED PROOF<br />

y i = F −1<br />

∗<br />

( i<br />

n + 1<br />

)<br />

. (1)<br />

Here we look at the “vertical” differences between the x (i) and y i . As we will 61<br />

see below it is this alternative view that is more fruitful for application to the 62<br />

inequality-measurement problem. 63<br />

2.1 Aggregation of information 64<br />

A divergence measure for the EDF and the reference distribution aggregrates 65<br />

discrepancies between the quantiles of the two distributions, for each value of q. 66<br />

Each discrepancy concerns an income pair (x i , y i )—the ith quantile in the two 67<br />

distributions—and the profile of these pairs captures all the essential information 68<br />

for the problem to which the divergence measure will be applied. We suggest that 69<br />

an appropriate divergence measure should satisfy the following principles: (1) If two 70


AUTHOR'S PROOF<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

F. A. Cowell et al.<br />

71<br />

72<br />

73<br />

74<br />

75<br />

76<br />

77<br />

78<br />

79<br />

80<br />

81<br />

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83<br />

84<br />

85<br />

86<br />

87<br />

88<br />

89<br />

90<br />

91<br />

92<br />

93<br />

94<br />

95<br />

profiles are equivalent in terms of divergence and the discrepancy for pair i is the<br />

same in each profile, then a local variation at i simultaneously in the two profiles has<br />

no overall effect. (2) If there is zero discrepancy at each of two pairs in the profile<br />

then moving x-income and y-income simultaneously from one pair to the other<br />

has no effect on divergence. (3) Divergence remains unchanged by a uniform scale<br />

change to x-values and y-values simultaneously. (4) Given two discrepancy profiles<br />

with the same aggregate divergence, rescaling all the income discrepancies in each<br />

profile by the same factor results in two new profiles that are equivalent in terms of<br />

divergence. 4<br />

Using the result in Theorem 1 (in the Appendix) and normalising on the case<br />

where both the observed and the reference distribution exhibit complete equality,<br />

these principles gives the following class of measures:<br />

( ) 1<br />

J α x, y :=<br />

nα(α − 1)<br />

[<br />

n∑ [ ] α [ ] ]<br />

1−α xi yi<br />

− 1 . (2)<br />

μ 1 μ 2<br />

i=1<br />

( )<br />

where α takes any real value 5 and J α x, y ≥ 0 for arbitrary x and y. 6 There is an<br />

analogy with the Kullback and Leibler [26] index of relative entropy [10].<br />

So a divergence measure for the EDF and a theoretical reference distribution<br />

(<br />

F ∗<br />

would be given by replacing x i and y i in Eq. 2, respectively, by EDF∗<br />

−1 i<br />

)<br />

n+1 = x(i)<br />

(<br />

and F∗<br />

−1 i<br />

)<br />

:<br />

7<br />

n+1<br />

1<br />

J α =<br />

nα(α − 1)<br />

⎡<br />

n∑<br />

i=1<br />

⎣[<br />

x(i)<br />

] [ α<br />

(<br />

F<br />

−1 i<br />

) ] 1−α<br />

∗ n+1<br />

− 1⎤<br />

⎦ ,α̸= 0, 1. (3)<br />

ˆμ μ (F ∗ )<br />

The J index can be used to measure the divergence between an empirical income<br />

distribution, given by a sample of individual incomes, and any theoretical reference<br />

distribution. It requires the choice of specific values for the parameter α according<br />

to the judgment that one wants to make about the relative importance of different<br />

types of discrepancy: choosing a large positive value for α puts weight on parts of the<br />

distribution where the observed incomes x i greatly exceed the corresponding values<br />

y i in the reference distribution; choosing a substantial negative value puts weight on<br />

cases where the opposite type of discrepancy arises.<br />

UNCORRECTED PROOF<br />

4 SeeAxioms4,5,6,7intheAppendix.<br />

5 ( )<br />

J 0 x, y =−<br />

1 ∑ ( )<br />

ni=1 y i<br />

n μ 2<br />

log xi<br />

μ 1<br />

/ y ( )<br />

i<br />

μ 2<br />

, J 1 x, y =<br />

1 ∑ ( ni=1 x i<br />

n μ 1<br />

log xi<br />

μ 1<br />

/ y i<br />

μ 2<br />

).<br />

6 ( ) ∑<br />

To see this write J α x, y as ni=1 y i<br />

[<br />

nμ 2<br />

ψ (qi ) − ψ (1) ] , where q i := x iμ 2<br />

y i μ 1<br />

,ψ(q) :=<br />

qα<br />

α[α−1] Because<br />

ψ is convex function, for any (q 1 , ..., q n ) and any set of non negative weights (w 1 , ..., w n ) that sum<br />

to 1, ∑ n<br />

i=1 w i ψ (q i ) ≥ ψ (∑ n )<br />

i=1 w i q i . Letting wi = y i / [nμ 2 ] and using the definition of q i we can see<br />

that w i q i = x i / [nμ 1 ] so we have ∑ n<br />

i=1 w i ψ (q i ) ≥ ψ (1) and the result follows. See also [6].<br />

7 The limiting forms are J 0 =−n<br />

1<br />

( ( ))<br />

1 ∑ i<br />

ni=1 x (i)<br />

n ˆμ log x (i)<br />

ˆμ / F−1 ∗ n+1<br />

μ(F ∗) .<br />

(<br />

∑ ni=1<br />

F∗<br />

−1 i<br />

n+1<br />

μ(F ∗)<br />

)<br />

log<br />

(<br />

( ) i<br />

x (i)<br />

ˆμ / F−1 ∗ n+1<br />

μ(F ∗)<br />

)<br />

, J 1 =


AUTHOR'S PROOF<br />

Reference distributions and inequality measurement<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

Q2<br />

Fig. 2 Quantile approach with<br />

the most equal reference<br />

distribution<br />

x<br />

Q3<br />

°<br />

°<br />

°<br />

°<br />

Δ x 3<br />

°<br />

x 3<br />

F −1 *<br />

(·)<br />

1<br />

2.2 Reference distributions 96<br />

The use of the J index also requires the specification of a reference distribution: there 97<br />

are several possibilities. 98<br />

The most equal reference distribution Let us assume that the most equal income 99<br />

distribution is when the same amount is given to each individuals:<br />

100 Q4<br />

( ) i<br />

F∗<br />

−1 =ˆμ for i = 1,...,n (4)<br />

n + 1<br />

If we use this (egalitarian) distribution as the reference distribution in Eq. 3,thenwe 101<br />

find the standard Generalised Entropy inequality measure: 8 102<br />

1<br />

n∑<br />

[( ) α xi<br />

J α =<br />

− 1]<br />

,α̸= 0, 1 (5)<br />

nα(α − 1) ˆμ<br />

UNCORRECTED PROOF<br />

i=1<br />

So the GE inequality measures are divergence measures between the EDF and the 103<br />

most equal distribution, where everybody gets the same income. They tell us how far 104<br />

a distribution is from the most equal distribution. A sample with a smaller index has 105<br />

amoreequal distribution. 106<br />

Figure 2 presents the quantile approach for this case. We can see that the EDF is 107<br />

always above (below) the reference distribution for large (small) values of incomes. 108<br />

It makes clear that large (small) values of α would be more sensitive to changes in 109<br />

high (small) incomes. 110<br />

8 The limiting forms are J 0 =−n 1 ∑ ( )<br />

ni=1<br />

log xi<br />

, J ˆμ 1 = n 1 ∑ ( )<br />

ni=1 x i<br />

ˆμ log xi<br />

. ˆμ


AUTHOR'S PROOF<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

F. A. Cowell et al.<br />

111<br />

112<br />

113<br />

114<br />

115<br />

116<br />

117<br />

118<br />

119<br />

120<br />

121<br />

122<br />

123<br />

124<br />

125<br />

126<br />

127<br />

128<br />

129<br />

130<br />

131<br />

132<br />

133<br />

134<br />

135<br />

136<br />

137<br />

The most unequal reference distribution Rather than selecting the most equal<br />

distribution as a reference distribution, we can reverse the standard approach by<br />

using the most unequal distribution as a reference distribution. The most unequal<br />

income distribution is when one person gets all the income and the others zero:<br />

( ) {<br />

i<br />

F∗<br />

−1<br />

0 for i = 1,...,n − 1<br />

=<br />

n + 1 n ˆμ for i = n<br />

If we use this distribution as the reference distribution in Eq. 3, then we have: 9<br />

[( )<br />

1 max α xi<br />

J α =<br />

− 1]<br />


AUTHOR'S PROOF<br />

Reference distributions and inequality measurement<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

Q2<br />

where 10 138<br />

{<br />

(1 − p)/(1 − k) if i ≤⌈n(1 − k)⌉<br />

c i =<br />

(10)<br />

p/k<br />

if i > ⌈n(1 − k)⌉<br />

There are two interesting special cases. If p = k, everybody gets the same income 139<br />

value, ˆμ, and the reference distribution is the most equal distribution. If k = 1/n and 140<br />

p = 1, only one individual gets all the income, n ˆμ, and the reference distribution is 141<br />

the most unequal distribution. 142<br />

In practice, k and p have to be fixed: (1) to avoid the first drawback, k and p 143<br />

should be independent of the sample size, with k > 1/n and p > 1/n ; (2) to avoid 144<br />

the second drawback, zero incomes are not allowed in the reference distribution, that 145<br />

is, if p = 1 we have k = 1.Finally,tomakeourindexJ α,k,p useful in practice, we need 146<br />

to use constant values, such that 147<br />

1/n < k < 1 and 1/n < p < 1, or p = k = 1. (11)<br />

In empirical studies, we could use several values of k and p. For instance, k = 1 − 148<br />

p = 0.05, 0.01, 0.005, correspond to the reference distributions with the top 5 %, 1 % 149<br />

and 0.5 % getting, respectively, 95 %, 99 % and 99.5 % of the total income. 150<br />

Other reference distributions Clearly, other reference distributions could be used. 151<br />

For instance, if we assume that productive talents are distributed in the population 152 Q4<br />

according to a continuous distribution of talents F ∗ and that wages should be related 153<br />

to talent, a situation in which everyone received the same income to everybody 154<br />

might be considered as unfair. In this case one might use F ∗ as the reference 155<br />

distribution and make use of the index (Eq. 3): any deviation from F ∗ would come 156<br />

from something else than talent. If total income is finite, it makes sense to use 157<br />

a distribution defined on a finite support. For instance, we could use a Uniform 158<br />

distribution or a Beta distribution with two parameters, which can provide a variety 159<br />

of appropriate shapes. 160<br />

3 Implementation 161<br />

UNCORRECTED PROOF<br />

It is necessary to establish the existence of an asymptotic distribution for J α and J α,k,p 162<br />

in order to justify its use in practice. If the most equal distribution is taken as the 163<br />

reference distribution (k = p = 1), the index J α,1,1 is nothing but the standard GE 164<br />

inequality measure, which is asymptotically Normal and has well-known statistical 165<br />

properties. 11 If a continuous distribution is taken as the reference distribution, it can 166<br />

be shown that the limiting distribution of nJ α is that of 167<br />

[ ∫<br />

1 1<br />

B 2 (t)dt<br />

2μ F∗ 0 F∗<br />

−1 (t) f∗ 2(F−1<br />

∗ (t)) − 1 (∫ 1<br />

) 2<br />

]<br />

B(t)dt<br />

μ F∗ 0 f ∗ (F∗<br />

−1<br />

(12)<br />

(t))<br />

10 The limiting forms are J 0,k,p =−n 1 ∑ ( )<br />

ni=1 x(i)<br />

c i log , J c i ˆμ 1,k,p = n<br />

1 ∑ ni=1 x (i)<br />

ˆμ<br />

( )<br />

log<br />

x(i)<br />

. c i ˆμ<br />

11 Among others, see Cowell and Flachaire [9], Davidson and Flachaire [12], Schluter and van<br />

Garderen [31], Schluter [30], Davidson [11].


AUTHOR'S PROOF<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

F. A. Cowell et al.<br />

168 where f ∗ is the density of distribution F ∗ and B(t) is a Brownian bridge. This random<br />

169 variable can have an infinite expectation. It is only if F ∗ has a bounded support<br />

170 that the limiting distribution has reasonable properties—see Cowell et al. [8] and<br />

171 Davidson [11] for more details. If we use a continuous parametric reference distri-<br />

172 bution, since total income is finite, it makes sense to use a distribution F ∗ defined<br />

173 on a bounded support only. For instance, one could use a Uniform distribution or<br />

174 a Beta distribution with two parameters, which can provide many different shapes.<br />

175 The same approach can be used for nJ α,k,p , noting that the last statistic is equivalent<br />

176 to the statistic defined in (9) in Cowell et al. [8], where 2i/(n + 1) is replaced by c i<br />

177 defined in Eq. 10.<br />

178 In the two cases, the limiting distribution of J α and J α,k,p exists, but is not<br />

179 tractable. This is enough to justify the use of bootstrap methods for making inference.<br />

180 To compute a bootstrap confidence interval, we generate B bootstrap samples by<br />

181 resampling from the original data, and then, for each resample, we compute the<br />

182 index J. We obtain B bootstrap statistics, Jα b , b = 1,...,B. The percentile bootstrap<br />

183 confidence interval is equal to<br />

CI perc = [ c b 0.025 ; ]<br />

cb 0.975<br />

(13)<br />

184 where c b 0.025 and cb 0.975<br />

are the 2.5 and 97.5 percentiles of the EDF of the bootstrap<br />

185 statistics—for a comprehensive discussion on bootstrap methods, see Davison and<br />

186 Hinkley [17], Davidson and MacKinnon [15]. For well-known reasons [14, 17] the<br />

187 number B should be chosen so that (B + 1)/100 is an integer: here we set B = 999<br />

188 unless otherwise stated.<br />

189 To be used in practice, we need to determine the finite sample properties of J α<br />

190 and J α,k,p . The coverage error rate of a confidence interval is the probability that<br />

191 the random interval does not cover the true value of the parameter. A method of<br />

192 constructing confidence intervals with good finite sample properties should generate<br />

193 a coverage error rate close to the nominal rate. For a confidence interval at 95 %,<br />

194 the nominal coverage error rate is equal to 5 %. We use Monte-Carlo simulation<br />

195 to approximate the coverage error rate bootstrap confidence intervals in several<br />

196 experimental designs.<br />

197 In our experiments, samples are drawn from a lognormal distribution. For fixed<br />

198 values of α, k, p and n, we draw 10,000 samples. For each sample we compute J α or<br />

199 J α,k,p and its confidence interval at 95 %. The coverage error rate is computed as<br />

200 the proportion of times the true value of the inequality measure is not included in<br />

201 the confidence intervals. 12 Confidence intervals perform well in finite samples if the<br />

202 coverage error rate is close to the nominal value, 0.05.Table1 presents the coverage<br />

203 error rate of bootstrap confidence intervals at 95 % of J α and J α,k,p for several<br />

204 reference distributions. The standard GE measures use the most equal reference<br />

205 distribution, it corresponds to J α,1,1 .When“thetop1%richestgets99%ofthe<br />

206 income” is the reference distribution we use the index J α,0.01,0.99 ; when “the top<br />

207 5 % richest gets 99 % of the income” is the reference distribution we use J α,0.05,0.99 .<br />

208 In addition, we examine J α with two continuous (bounded) parametric reference<br />

209 distributions, the Beta(1,1) distribution which is equal to the Uniform(0,1), and the<br />

UNCORRECTED PROOF<br />

12 The true values are computed replacing x (i) in Eq. 3 by F −1 ( n+1 i ),whereF is the distribution of x,<br />

that is, the lognormal distribution in our experiments.


AUTHOR'S PROOF<br />

Reference distributions and inequality measurement<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

Q2<br />

Q5 t1.1 Table 1 Coverage error rate of bootstrap confidence intervals at 95 % of J α and J α,k,p , 10,000<br />

replications, 499 bootstraps, and x ∼ Lognormal(0, 1)<br />

t1.2 α −1 0 0.5 1 2<br />

Equal reference distribution<br />

Standard GE measures (k = p = 1)<br />

t1.3 n = 100 0.0753 0.0734 0.0832 0.0912 0.1166<br />

t1.4 n = 200 0.0747 0.0667 0.0713 0.0785 0.1024<br />

t1.5 n = 500 0.0669 0.0673 0.0716 0.0781 0.0983<br />

t1.6 n = 1000 0.0658 0.0606 0.0642 0.0709 0.0878<br />

t1.7 n = 2000 0.0567 0.0565 0.0620 0.0658 0.0831<br />

t1.8 n = 5000 0.0557 0.0562 0.0606 0.0672 0.0809<br />

Unequal reference distributions<br />

Top 5 % gets 99 % of the income (k = 0.05, p = 0.99)<br />

t1.9 n = 100 0.0722 0.0887 0.0983 0.1005 0.0395<br />

t1.10 n = 200 0.0597 0.0662 0.0733 0.0813 0.0482<br />

t1.11 n = 500 0.0594 0.0577 0.0638 0.0681 0.0584<br />

t1.12 n = 1000 0.0553 0.0543 0.0572 0.0619 0.0575<br />

t1.13 n = 2000 0.0581 0.0557 0.0552 0.0590 0.0564<br />

t1.14 n = 5000 0.0526 0.0531 0.0562 0.0588 0.0569<br />

Top 1 % gets 99 % of the income (k = 0.01, p = 0.99)<br />

t1.15 n = 100 0.2220 0.2221 0.2172 0.1347 0.0325<br />

t1.16 n = 200 0.1601 0.1689 0.1705 0.1265 0.0275<br />

t1.17 n = 500 0.0998 0.1117 0.1188 0.1064 0.0346<br />

t1.18 n = 1000 0.0703 0.0788 0.0867 0.0878 0.0422<br />

t1.19 n = 2000 0.0581 0.0642 0.0682 0.0717 0.0486<br />

t1.20 n = 5000 0.0558 0.0598 0.0616 0.0627 0.0504<br />

Continuous reference distributions<br />

Beta(1,1)<br />

t1.21 n = 100 0.0830 0.0877 0.0923 0.0981 0.1162<br />

t1.22 n = 200 0.0703 0.0756 0.0805 0.0865 0.1029<br />

t1.23 n = 500 0.0689 0.0740 0.0778 0.0847 0.1011<br />

t1.24 n = 1000 0.0650 0.0674 0.0710 0.0766 0.0905<br />

t1.25 n = 2000 0.0605 0.0632 0.0645 0.0700 0.0838<br />

t1.26 n = 5000 0.0623 0.0638 0.0660 0.0715 0.0824<br />

Beta(2,2)<br />

t1.27 n = 100 0.0778 0.0841 0.0896 0.0945 0.1122<br />

t1.28 n = 200 0.0680 0.0730 0.0764 0.0832 0.1002<br />

t1.29 n = 500 0.0694 0.0722 0.0762 0.0829 0.0988<br />

t1.30 n = 1000 0.0611 0.0656 0.0682 0.0742 0.0885<br />

t1.31 n = 2000 0.0574 0.0626 0.0636 0.0679 0.0834<br />

t1.32 n = 5000 0.0584 0.0632 0.0651 0.0694 0.0816<br />

UNCORRECTED PROOF<br />

Beta(2,2) which is a symmetric inverted-U-shape distribution. Table 1 shows that 210<br />

the finite sample properties of the indices with alternative reference distributions are 211<br />

not very diferent from those of the standard GE measures, except for J α,0.01,0.99 when 212<br />

n ≤ 500. The coverage error rate is close to 0.05 for very large samples. For small 213<br />

and moderate samples, further investigation is required to improve the finite sample 214<br />

properties, with, for instance, a fast double or triple bootstrap [13, 16]. 215


AUTHOR'S PROOF<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

F. A. Cowell et al.<br />

216<br />

217<br />

218<br />

219<br />

220<br />

4 Application<br />

Let us compare the performance of J α,k,p with that of conventional GE inequality<br />

measures using UK income data as a case study. 13 Table 2 presents the results of<br />

indices J α and J α,k,p estimated with three different types of reference distribution,<br />

along with bootstrap confidence intervals at 95 %.<br />

221<br />

222<br />

223<br />

224<br />

225<br />

226<br />

227<br />

228<br />

229<br />

230<br />

231<br />

232<br />

233<br />

234<br />

235<br />

236<br />

237<br />

238<br />

239<br />

240<br />

241<br />

242<br />

243<br />

244<br />

245<br />

246<br />

247<br />

248<br />

249<br />

250<br />

251<br />

252<br />

Equality The top panel of Table 2 presents estimates of J α,k,p using an “equality” Q4<br />

reference distribution. Clearly, when we select the most equal distribution as the<br />

reference distribution, i.e. k = p = 1, the index J α,k,p is reduced to the standard GE<br />

inequality measure. Estimates for standard GE measures, J α,1,1 are tabulated in the<br />

first row, for values of α ranging from −1 to 2. 14 When α = 1, J α,1,1 is the Theil<br />

index. For values of α = 0.5, 1, 1.5, 2, J α,1,1 represents transformed Atkinson indices<br />

[7]. All estimates of standard GE measures increase considerably between 1979 and<br />

1988, suggesting a significant rise in inequality in the 80s.<br />

Extreme inequality The key point highlighted earlier was that changing the refer- Q4<br />

ence distribution from which we measure the distance of the empirical distribution<br />

opens up the possibility for researchers to choose the exact distribution from which<br />

they wish to measure distance of the empirical distribution. While standard GE<br />

indices tell us about the distance of the empirical distribution from an equal reference<br />

distribution, one can change the focus to that of its distance from an unequal<br />

reference distribution. The second panel of Table 2 presents estimates of J α,k,p using<br />

several “extreme inequality” reference distributions. The interpretation of the size<br />

of the J α,k,p index now is the reverse of the interpretation of standard GE measures.<br />

For a standard GE inequality measure, a small value of J α,1,1 corresponds to the<br />

empirical distribution being close to the equal reference distribution compared to<br />

that of a large value of J α,1,1 . However, for an unequal reference distribution a small<br />

value of J α,k,p corresponds to the empirical distribution being close to the particular<br />

“extreme inequality” reference distribution that has been specified.<br />

To illustrate we focus on two different unequal reference distributions: one, where<br />

the top 1 % of the income distribution receive 99 % of the income, and second,<br />

where the top 5 % of the income distribution receive 99 % of the income. From<br />

Table 2 we can see that, with one exception, the values of J α,k,p have dropped<br />

between years 1979 and 1988: in other words, it is almost always true that the distance<br />

from the “extreme inequality” reference distribution has decreased. The exception<br />

is the case (k = 0.05, p = 0.99,α = 2) where the movement relative to the reference<br />

distribution is not significant. The implication is that UK inequality grew during the<br />

1980s whether one interprets this in terms of distance from equality, or as distance<br />

from a reference unequal distribution, except for one case. This case concerns top-<br />

UNCORRECTED PROOF<br />

13 The application uses the “before housing costs” income variable of the Family Expenditure Survey<br />

for years 1979 and 1988 [18], deflated and equivalised using the McClements adult-equivalence<br />

scale. We exclude households with self-employed individuals as reported incomes are known to be<br />

misrepresented. The years 1979 and 1988 have been chosen to represent the maximum recorded<br />

difference in inequality across the available years, post-1975.<br />

14 A large value of α implies greater weight on parts of the distribution where the observed incomes<br />

are vastly different from the corresponding values in the reference distribution.


AUTHOR'S PROOF<br />

Reference distributions and inequality measurement<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

Q2<br />

Q5 t2.1 Table 2 Inequality indices Jα,k,p and Jα computed with different reference distributions<br />

t2.2 α −1 0 0.5 1 2<br />

Equal reference distribution<br />

Standard GE measures (k = p = 1)<br />

t2.3 1979 0.1218 0.1056 0.1046 0.1066 0.1201<br />

t2.4 [0.1119;0.1355] [0.1016;0.1097] [0.1005;0.1086] [0.1023;0.1111] [0.1132;0.1271]<br />

t2.5 1988 0.1836 0.1541 0.1543 0.1618 0.2096<br />

t2.6 [0.1685;0.2018] [0.1468;0.1613] [0.1460;0.1634] [0.1508;0.1728] [0.1843;0.2381]<br />

Unequal reference distributions<br />

Top 1 % gets 99 % of the income (k = 0.01, p = 0.99)<br />

t2.7 1979 15.29 3.370 2.906 4.403 55.39<br />

t2.8 [14.46;16.21] [3.315;3.427] [2.887;2.926] [4.390;4.419] [55.05;55.75]<br />

t2.9 1988 11.70 3.086 2.795 4.341 57.97<br />

t2.10 [10.59;12.792] [2.982;3.182] [2.749;2.836] [4.300;4.378] [57.32;58.66]<br />

Top 5 % gets 99 % of the income (k = 0.05, p = 0.99)<br />

t2.11 1979 3.803 2.080 2.271 3.768 44.43<br />

t2.12 [3.708;3.907] [2.057;2.106] [2.254;2.288] [3.747;3.789] [44.08;44.74]<br />

t2.13 1988 3.194 1.915 2.151 3.631 44.14<br />

t2.14 [3.088;3.293] [1.882;1.945] [2.123;2.175] [3.591;3.665] [43.47;44.73]<br />

Continuous reference distributions<br />

Beta(1,1) or Uniform(0,1)<br />

t2.15 1979 0.0320 0.0406 0.0483 0.0613 0.1457<br />

t2.16 [0.0308;0.0333] [0.0391;0.0421] [0.0465;0.0501] [0.0589;0.0638] [0.1311;0.1648]<br />

t2.17 1988 0.0339 0.0418 0.0486 0.0591 0.1125<br />

t2.18 [0.0313;0.0373] [0.0383;0.0461] [0.0444;0.0536] [0.0538;0.0655] [0.1014;0.1276]<br />

UNCORRECTED PROOF


AUTHOR'S PROOF<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

F. A. Cowell et al.<br />

UNCORRECTED PROOF<br />

Q5 t2.1 Table 2 (continued)<br />

t2.2 α −1 0 0.5 1 2<br />

Beta(2,2)<br />

t2.3 1979 0.0115 0.0132 0.0143 0.0158 0.0199<br />

t2.4 [0.0105;0.0127] [0.0121;0.0146] [0.0131;0.0158] [0.0144;0.0175] [0.0181;0.0222]<br />

t2.5 1988 0.0210 0.0243 0.0267 0.0299 0.0405<br />

t2.6 [0.0180;0.0242] [0.0204;0.0283] [0.0221;0.0316] [0.0242;0.0362] [0.0300;0.0524]<br />

Beta(2,5)<br />

t2.7 1979 0.0116 0.0138 0.0153 0.0173 0.0237<br />

t2.8 [0.0109;0.0124] [0.0129;0.0147] [0.0143;0.0163] [0.0162;0.0185] [0.0219;0.0256]<br />

t2.9 1988 0.0121 0.0142 0.0157 0.0175 0.0231<br />

t2.10 [0.0100;0.0145] [0.0116;0.0172] [0.0127;0.0192] [0.0141;0.0217] [0.0177;0.0294]<br />

t2.11 Data are from the Family Expenditures Surveys in UK. Bootstrap confidence intervals at 95 % are given in brackets


AUTHOR'S PROOF<br />

Reference distributions and inequality measurement<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

Q2<br />

sensitive inequality where, in terms of “distance from maximum inequality,” the 253<br />

change in the distribution is inconclusive. 254<br />

Theoretical distribution Finally let us consider how inequality changed using a con- 255 Q4<br />

tinuous reference distribution F ∗ . The last panel of Table 2 tabulates the results for 256<br />

three F ∗ from the Beta distribution family. Did UK income inequality, interpreted 257<br />

as a distance from a Beta-family reference distribution increase We can see that 258<br />

the values of J α are not statistically different between 1979 and 1988 when the 259<br />

Beta(1,1) (uniform) or Beta(2,5) (unimodal, right skewed) is used as the reference 260<br />

distribution distribution, while they are statistically different when the Beta(2, 2) 261<br />

(unimodal symmetric) is used as the reference distribution. 262<br />

The estimates of the standard GE inequality measures J α,1,1 and of those of J α,k,p 263<br />

and J α in Table 2 provide us with different information about divergence of the 264<br />

empirical distribution from the chosen reference distribution. By varying the values 265<br />

of k and p, one can specify the exact skewness of the reference distribution one would 266<br />

like to measure distance of the empirical distribution from. Likewise, by varying the 267<br />

values of α one can focus on different parts of the income distribution. A large value 268<br />

of α implies a greater weight on parts of the distribution where the observed incomes 269<br />

are vastly different from the corresponding values in the reference distribution. 270<br />

Finally, one can choose specific parametric distributions which correspond to the 271<br />

relevant reference distribution that the researcher is interested in. 272<br />

5 Conclusion 273<br />

The problem of comparing pairs of distributions is a widespread one in distributional 274<br />

analysis. It is often treated on an ad-hoc basis by invoking the concept of norm 275<br />

incomes and an arbitrary inequality index. 276<br />

Our approach to the issue is a natural generalisation of the concept of inequal- 277<br />

ity indices where the implicit reference distribution is the trivial perfect-equality 278<br />

distribution. Its intuitive appeal is supported by the type of axiomatisation that 279<br />

is common in modern approaches to inequality measurement and other welfare 280<br />

criteria. The axiomatisation yields indices that can be interpreted as measures of 281<br />

divergence and are related to the concept of divergence entropy in information 282<br />

theory [10]. Furthermore, they offer a degree of control to the researcher in that 283<br />

the J α indices form a class of measures that can be calibrated to suit the nature of the 284<br />

economic problem under consideration. Members of the class have a distributional 285<br />

interpretation that is close to members of the well-known generalised-entropy class 286<br />

of inequality indices. 287<br />

In effect the user of the J α -index is presented with two key questions: 288<br />

UNCORRECTED PROOF<br />

1. the income discrepancies underlying inequality are with reference to what 289<br />

2. to what kind of discrepancies do you want the measure to be particularly 290<br />

sensitive 291<br />

As our empirical illustration has shown, different responses to these two key ques- 292<br />

tions provide different interpretations from the same set of facts. 293


AUTHOR'S PROOF<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

F. A. Cowell et al.<br />

294<br />

Appendix: Axiomatic foundation<br />

295 For convenience we work with z :=(z 1 , z 2 , ..., z n ), where each z i is the ordered pair<br />

296 (x i , y i ), i = 1, ..., n and belongs to a set Z , which we will take to be a connected<br />

297 subset of R + × R + . For any z ∈ Z n denote by z (ζ,i) the member of Z n formed<br />

298 by replacing the ith component of z by ζ ∈ Z . The divergence issue focuses on the<br />

299 discrepancies between the x-values and the y-values. To capture this introduce a<br />

300 discrepancy function d : Z → R such that d (z i ) is strictly increasing in |x i − y i |.The<br />

301 solution is in two steps: (1) characterise a weak ordering ≽ on Z n (z ≽ z ′ means “the<br />

302 income pairs in z are at least as close according to ≽ as the income pairs in z ′ ”) (2)<br />

303 use the function representing ≽ to generate the index J.<br />

304<br />

Axiom 1 (Continuity) ≽ is continuous on Z n .<br />

305 Axiom 2 (Monotonicity) If z, z ′ ∈ Z n differ only in their ith component then<br />

d (x i , y i ) < d ( 306<br />

x<br />

i ′, i) y′ ⇐⇒ z ≻ z ′ .<br />

307 Axiom 3 (Symmetry) For any z, z ′ ∈ Z n such that z ′ is obtained by permuting the<br />

308 components of z: z ∼ z ′ .<br />

309 Axiom 3 implies that we may order the components of z such that x 1 ≤ x 2 ≤ ... ≤<br />

310 x n and y 1 ≤ y 2 ≤ ... ≤ y n .<br />

311 Axiom 4 (Independence) For z, z ′ ∈ Z n such that: z ∼ z ′ and z i = z<br />

i ′ for some i then<br />

z (ζ,i) ∼ z ′ (ζ,i) for all ζ ∈ [ ] [ ]<br />

312 z i−1 , z i+1 ∩ z<br />

′<br />

i−1<br />

, z<br />

i+1<br />

′ .<br />

313 Axiom 5 (Zero local discrepancy) Let z, z ′ ∈ Z n be such that, for some i and j, x i =<br />

314 y i , x j = y j , x<br />

i ′ = x i + δ, y<br />

i ′ = y i + δ, x ′ j = x j − δ, y ′ j = y j − δ and, for all k ̸= i, j, x ′ k =<br />

315 x k , y ′ k = y k.Thenz ∼ z ′ .<br />

316 Axiom 6 (Income scale irrelevance) For any z, z ′ ∈ Z n such that z ∼ z ′ , tz ∼ tz ′ for<br />

317 all t > 0.<br />

UNCORRECTED PROOF<br />

318 Axiom 7 (Discrepancy scale irrelevance) Suppose there are z 0 , z ′ 0 ∈ Z n such that<br />

z 0 ∼ z ′ 0 . Then for all t > 0 and z, z′ such that d (z) = td (z 0 ) and d ( z ′) = td ( 319<br />

z 0) ′ : z ∼ z ′ .<br />

320<br />

321<br />

322<br />

323<br />

324<br />

325<br />

326<br />

327<br />

Lemma 1 Given Axioms 1 to 5 (a) ≽ is representable by ∑ n<br />

i=1 φ i (z i ) , ∀z ∈ Z n where,<br />

for each i, φ i : Z → R is a continuous function that is strictly decreasing in |x i − y i |<br />

and (b) φ i (x, x) = a i + b i x.<br />

Proof Axioms 1 to 5 imply that ≽ can be represented by a continuous function :<br />

Z n → R that is increasing in |x i − y i |, i = 1, ..., n. Part (a) of the result follows from<br />

Axiom 4 and Theorem 5.3 of [23]. Now take z<br />

( ′ and z as specified in Axiom 5: z ∼ z ′ if<br />

and only if φ i (x i + δ, x i + δ) − φ i (x i , x i ) − φ j x j + δ, x j + δ ) (<br />

+ φ j x j + δ, x j + δ ) = 0<br />

which implies<br />

φ i (x i + δ, x i + δ) − φ i (x i , x i ) = f (δ)<br />

328 for any x i and δ. The solution to this Pexider equation implies (b).


AUTHOR'S PROOF<br />

Reference distributions and inequality measurement<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

Q2<br />

Lemma 2 Given Axioms 1 to 6 ≽ is representable by φ<br />

( ∑n<br />

i=1 x ih i<br />

(<br />

xi<br />

y i<br />

))<br />

where h i is a 329<br />

real-valued function. 330<br />

Proof Using the function introduced in the <strong>proof</strong> of Lemma 1 Axiom 6 implies 331<br />

(z) = ( z ′) and (tz) = ( tz ′) ; since this has to be true for arbitrary z, z ′ we have 332<br />

(tz)<br />

(z) = ( tz ′)<br />

(z ′ ) = ψ (t)<br />

where ψ is a continuous function R → R. Hence,usingtheφ i given in Lemma 1 we 333<br />

have for all i : φ i (tz i ) = ψ (t) φ i (z i ) or, equivalently φ i (tx i , ty i ) = ψ (t) φ i (x i , y i ) . In 334<br />

view of Aczél and Dhombres [2], page 346 there must exist c ∈ R and a function 335<br />

h i : R + → R such that 336<br />

( )<br />

φ i (x i , y i ) = xi c h xi<br />

i . (14)<br />

y i<br />

From Lemma 1 and Eq. 14: φ i (x i , x i ) = xi ch i (1) = a i + b i x i , which, ifφ i (x, x) is non- 337<br />

constant in x, implies c = 1. Noting that Lemma 1 implies that ≽ is also representable 338<br />

by φ (∑ n<br />

i=1 φ i (z i ) ) (whereφ : R → R is continuous and monotonic increasing, and 339<br />

taking Eq. 14 with c = 1 gives the result. ⊓⊔ 340<br />

Theorem 1 Given Axioms 1 to 7 ≽ is representable by φ (∑ n<br />

)<br />

i=1 xα i y1−α i where α ̸= 1 341<br />

is a constant. 342<br />

Proof (Cf [21]) Take the special case where, in distribution z ′ 0<br />

the income discrep- 343<br />

ancy takes the same value r for all n income pairs. If (x i , y i ) represents a typical 344<br />

component in z 0 then z 0 ∼ z ′ 0<br />

implies 345<br />

( n∑ ( ) )<br />

xi<br />

r = ψ x i h i (15)<br />

y<br />

i=1 i<br />

where ψ is the solution in r to 346<br />

n∑<br />

( )<br />

xi<br />

n∑<br />

x i h i = x i h i (r) (16)<br />

y i<br />

UNCORRECTED PROOF<br />

i=1<br />

i=1<br />

In Eq. 16 we take the x i as fixed weights. Using Axiom 7 in Eq. 15 requires 347<br />

( n∑ (<br />

tr = ψ x i h i t x ) )<br />

i<br />

,forallt > 0. (17)<br />

y<br />

i=1<br />

i<br />

Using Eq. 16 we have 348<br />

(<br />

n∑<br />

n∑ ( )<br />

x i h i<br />

(tψ<br />

)) xi<br />

n∑<br />

(<br />

x i h i = x i h i t x )<br />

i<br />

(18)<br />

y<br />

i=1<br />

i=1 i y<br />

i=1<br />

i<br />

Introduce the following change of variables 349<br />

( )<br />

xi<br />

u i := x i h i , i = 1, ..., n (19)<br />

y i


AUTHOR'S PROOF<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

F. A. Cowell et al.<br />

350<br />

and write the inverse of this relationship as<br />

351<br />

352<br />

353<br />

354<br />

355<br />

356<br />

357<br />

358<br />

x i<br />

= ψ i (u i ) , i = 1, ..., n<br />

y i<br />

(20)<br />

Substituting Eqs. 19 and 20 into Eq. 18 we get<br />

(<br />

n∑<br />

n∑<br />

))<br />

n∑<br />

x i h i<br />

(tψ u i = x i h i (tψ i (u i )) .<br />

i=1<br />

i=1<br />

i=1<br />

(21)<br />

Also define the following functions θ 0 (u, t) := ∑ n<br />

i=1 x ih i (tψ (u)), θ i (u, t) :=<br />

x i h i (tψ i (u)) , i = 1, ..., n. Substituting these into Eq. 21:<br />

( n∑<br />

)<br />

n∑<br />

θ 0 u i , t = θ i (u i , t)<br />

i=1<br />

i=1<br />

which has as a solution<br />

θ i (u, t) = b i (t) + B (t) u, i = 0, 1, ..., n<br />

where b 0 (t) = ∑ n<br />

i=1 b i (t) ([1], p. 142). Therefore we have<br />

(<br />

h i t x )<br />

i<br />

= b ( )<br />

i (t)<br />

xi<br />

+ B (t) h i , i = 1, ..., n (22)<br />

y i x i<br />

y i<br />

From Eichhorn [22], Theorem 2.7.3 the solution to Eq. 22 is of the form<br />

{ }<br />

βi v<br />

h i (v) =<br />

+ γ i ,α̸= 1<br />

β i log v + γ i α = 1<br />

(23)<br />

where β i > 0 is arbitrary. Lemma 2 and Eq. 23 give the result.<br />

⊓⊔<br />

References<br />

359 1. Aczél, J.: Lectures on Functional Equations and their Applications. Number 9 in Mathematics in<br />

360 Science and Engineering. Academic Press, New York (1966)<br />

361 2. Aczél, J., Dhombres, J.G.: Functional Equations in Several Variables. Cambridge University<br />

362 Press, Cambridge (1989)<br />

363 3. Almås, I., Cappelen, A.W., Lind, J.T., Sorensen, E.O., Tungodden, B.: Measuring unfair<br />

364 (in)equality. J. Public Econ. 95(7–8), 488–499 (2011)<br />

365 4. Almås, I., Havnes, T., Mogstad, M.: Baby booming inequality demographic change and earnings<br />

366 inequality in Norway, 1967–2000. J. Econ. Inequal. 9, 629–650 (2011)<br />

367 5. Bartels, C.P.A.: Economic Aspects of Regional Welfare, Income Distribution and Unemploy-<br />

368 ment, Volume 9 of Studies in applied regional science. Leiden: Martinus Nijhoff Social Sciences<br />

Q6 369 Division (1977)<br />

370 6. Cowell, F.A.: Generalized entropy and the measurement of distributional change. Eur. Econ.<br />

371 Rev. 13, 147–159 (1980)<br />

372 7. Cowell, F.A.: Measuring Inequality, 3rd edn. Oxford University Press, Oxford (2011)<br />

373 8. Cowell, F.A., Davidson, R., Flachaire, E.: Goodness of fit: an axiomatic approach. Working Paper<br />

Q6 374 2011/50, Greqam (2011)<br />

375 9. Cowell, F.A., Flachaire, E.: Income distribution and inequality measurement: the problem of<br />

376 extreme values. J. Econom. 141, 1044–1072 (2007)<br />

377 10. Cowell, F.A., Flachaire, E., Bandyopadhyay, S.: Goodness-of-fit: An economic approach. Distri-<br />

378 butional Analysis Discussion Paper 101, STICERD, LSE, Houghton St., London, WC2A 2AE<br />

Q6 379 (2009)<br />

380 11. Davidson, R.: Statistical inference in the presence of heavy tails. Econom. J. 15, C31–C53 (2012)<br />

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Reference distributions and inequality measurement<br />

JrnlID 10888_ArtID 9238_Proof# 1 - 08/01/13<br />

Q2<br />

12. Davidson, R., Flachaire, E.: Asymptotic and bootstrap inference for inequality and poverty 381<br />

measures. J. Econom. 141, 141–166 (2007) 382<br />

13. Davidson, R., MacKinnon, J.: Improving the reliability of bootstrap tests with the fast double 383<br />

bootstrap. Comput. Stat. Data Anal. 51, 3259–3281 (2007) 384<br />

14. Davidson, R., MacKinnon, J.G.: Bootstrap tests: How many bootstraps Econom. Rev. 19, 55–68 385<br />

(2000) 386<br />

15. Davidson, R., MacKinnon, J.G.: Bootstrap methods in econometrics. In: Mills, T.C., Patterson, K. 387<br />

(eds.) Palgrave Handbook of Econometrics, vol. 1, Econometric Theory, Chapter 23. Palgrave- 388<br />

Macmillan, London (2006) 389<br />

16. Davidson, R., Trokic, M.: The iterated bootstrap. Paper presented at the Third French Econo- 390<br />

metrics Conference, Aix-en-Provence (2011) 391<br />

17. Davison, A.C., Hinkley, D.V.: Bootstrap Methods. Cambridge University Press, Cambridge 392<br />

(1997) 393<br />

18. Department of Work and Pensions: Households Below Average Income 1994/95-2004/05. TSO, 394<br />

London (2006) 395<br />

19. Devooght, K.: To each the same and to each his own: a proposal to measure responsibility- 396<br />

sensitive income inequality. Economica 75, 280–295 (2008) 397<br />

20. Ebert, U.: Measures of distance between income distributions. J. Econ. Theory 32, 266–274 398<br />

(1984) 399<br />

21. Ebert, U.: Measurement of inequality: an attempt at unification and generalization. Soc. Choice 400<br />

Welf. 5, 147–169 (1988) 401<br />

22. Eichhorn, W.: Functional Equations in Economics. Addison Wesley, Reading Massachusetts 402<br />

(1978) 403<br />

23. Fishburn, P.C.: Utility Theory for Decision Making. John Wiley, New York (1970) 404<br />

24. Garvy, G.: Inequality of income: causes and measurement. In: Eight Papers on Size Distribution 405<br />

of Income, vol. 15. National Bureau of Economic Research, New York (1952) 406<br />

25. Jenkins, S.P., O’Higgins, M.: Inequality measurement using norm incomes - were Garvy and 407<br />

Paglin onto something after all Rev. Income Wealth 35, 245–282 (1989) 408<br />

26. Kullback, S., Leibler, R.A.: On information and sufficiency. Ann. Math. Stat. 22, 79–86 (1951) 409<br />

27. Magdalou, B., Nock, R.: Income distributions and decomposable divergence measures. J. Econ. 410<br />

Theory 146, 2440–2454 (2011) 411<br />

28. Nygård, F., Sandström, A.: Measuring Income Inequality. Almquist Wicksell International, 412<br />

Stockholm, Sweden (1981) 413<br />

29. Paglin, M.: The measurement and trend of inequality: a basic revision. Am. Econ. Rev. 65, 598– 414<br />

609 (1975) 415<br />

30. Schluter, C.: On the problem of inference for inequality measures for heavy-tailed distributions. 416<br />

Econom. J. 15, 125–153 (2012) 417<br />

31. Schluter, C., van Garderen, K.: Edgeworth expansions and normalizing transforms for inequality 418<br />

measures. J. Econom. 150, 16–29 (2009) 419<br />

32. Wertz, K.: The measurement of inequality: comment. Am. Econ. Rev. 79, 670–72 (1979) 420<br />

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