Transcript Income Distribution Issues in Thailand Professor Medhi Krongkaew NACC Commissioner

Income Distribution Issues in Thailand
Professor Medhi Krongkaew
NACC Commissioner
Income Distribution
Income inequality as relative poverty
Theory of income distribution, sources and causes of
income inequality
Various measures of income distribution
Absolute vs. Relative Poverty
Absolute poverty is measured by poverty line, whereas relative
poverty is measured by the distribution of income of the
people, ie. how much income position of an individual deviates
from the mean income of the group, community, region, or
country. It is possible to have a situation where the distribution
of income is completely equal and all are under poverty.
Lorenz Curve and Gini Ratio
Lorenz curve shows the distribution of income of a group of
people where the number of people is cumulatively staggered
from poorest to richest, from 0 to 100 %, and plotted on the
horizontal axis of a unit square, and the cumulative income of
these people is plotted on the vertical axis. The curve that joins
all these coordinates is called the Lorenz Curve.
Lorenz Curve
%สะสมของรายใด้ (100%)
A
B
0
%สะสมของประชากร (100%)
ดัชนีวดั ความเหลือ่ มล้าของการกระจายรายได้.
(1)
เส้น Lorenz
% สะสมของรายได้ (100%)
A
B
00
% สะสมของประชากร (100%)
Lorenz Curve
%สะสมของรายใด้ (100%)
A
B
0
%สะสมของประชากร (100%)
ดัชนีวดั ความเหลือ่ มล้าของการกระจายรายได้ (ต่อ)
(2)
สัมประสิทธิ ์จินี (Gini coefficient)
G = A
A+B
(3)
สัดส่วนคนรวย/คนจน (T/B ratio)
TBR = รายได้ของกลุ่ม 20% ทีร่ วยทีส่ ดุ
รายได้ของกลุ่ม 20% ทีจ่ นทีส่ ดุ
Gini Ratio or Gini Coefficient
Measures income distribution as a ratio of area under the
Lorenz curve and the triangle under the diagonal line of
perfect equality.
G = A/(A+B)
G = 0 means perfectly equal income distribution; G = 1
means perfectly unequal income distribution
ดัชนีวดั ความเหลือ่ มล้าของการกระจายรายได้ (ต่อ)
(2)
สัมประสิทธิ ์จินี (Gini coefficient)
G = A
A+B
(3)
สัดส่วนคนรวย/คนจน (T/B ratio)
TBR = รายได้ของกลุ่ม 20% ทีร่ วยทีส่ ดุ
รายได้ของกลุ่ม 20% ทีจ่ นทีส่ ดุ
T/B Ratio
If all people are lined up from poorest to richest, or lowest to
highest income group, the ratio of total income of the top group
(richest) to the bottom group (poorest) or T/B Ratio would
signify how serious inequality of income is. If the population
is divided in to 5 equal groups (quintile), T/B ratio is the ratio
of Q5/Q1 where Q5 and Q1 are richest and poorest quintiles,
respectively
Marginal Productivity Theory of Distribution
If all factors in a competitive market are paid their values
of marginal products, then total resources are just
exhausted and distributed fairly to all factors of
production. The returns to each factor is determined by
how much it has put in the total national production or
income.
The Kuznets Hypothesis
Simon Kuznets concludes from his studies of the
relationship between economic growth and income
distribution that in the early stage of economic
development when the national income is growing, the
distribution of income will worsen first but will later
improve as the economy has grown past a certain level.
The Inverted U-Shaped Kuznets Curve
Index of
Inequality
Kuznets Curve
Income
Table 1b: Inequality of per capita welfare in Thailand
Gini
index
Series (b)
1975/76
1981
1986
1988
1990
1992
1994
1996
1998
1999
2000
Source: NSO
0.426
0.442
0.496
0.489
0.515
0.536
0.521
0.516
0.509
0.531
0.525
Quintile1 Quintile2 Quintile3 Quintile4 Quintile5 Quintile5/
Quintile1
6.0
5.5
4.5
4.6
4.3
4.0
4.0
4.1
4.2
3.8
3.9
9.7
9.3
7.9
8.0
7.5
7.1
7.3
7.5
7.7
7.1
7.2
14.0
13.7
12.3
12.4
11.7
11.1
11.7
11.8
11.9
11.4
11.4
21.0
21.1
20.3
20.6
19.5
18.8
19.7
19.9
19.8
19.4
19.7
49.2
50.4
55.0
54.5
57.0
59.1
57.2
56.7
56.3
58.2
57.8
8.1
9.2
12.2
11.9
13.2
14.9
14.2
13.8
13.3
15.2
14.9
2007
2006
2004
2002
2000
1998
1996
1994
1992
1990
1988
60
50
40
30
20
10
0
Q5
Q3
Q1