Micro-Determinants of Income Inequality
Micro-Determinants of Income Inequality
Micro-Determinants of Income Inequality
PEARL https://pearl.plymouth.ac.uk
Faculty of Science and Engineering School of Geography, Earth and Environmental Sciences
2015-12-15
Rahman, S
http://hdl.handle.net/10026.1/3953
All content in PEARL is protected by copyright law. Author manuscripts are made available in accordance with
publisher policies. Please cite only the published version using the details provided on the item record or
document. In the absence of an open licence (e.g. Creative Commons), permissions for further reuse of content
should be sought from the publisher or author.
Journal of Poverty Alleviation and International Development, 6(2)
©2015 The Author. Published by the Institute for Poverty Alleviation and International Development
under open access license CC BY-NC-ND 3.0.
Sanzidur RAHMAN**
noted that the authors from Asian countries, who used research data
collected in the Philippines and India, concluded that increasing
inequality is not associated with modern agricultural technology.
Understanding the precise causes and extent of poverty and
inequality has been a major concern of policy makers for some time, and
while regional differences exist, research has focussed on a fairly
constant set of variables. Particular household characteristics such as
education, land ownership, demography and potential sources of income,
as well as regional factors such as level of infrastructure development,
soil quality and fertility and location, are generally accepted as important
influences determining poverty and inequality but with mixed
influences. For example, Achia et al. (2010) noted that although
education significantly reduces the probability of being poor, rural
households are more likely to be poor as compared to their urban
counterparts in Kenya. They also noted that demographic factors such as
age, religion, ethnicity and region influence poverty. Rahman (2009)
noted that while land ownership, farm resource endowments and
non-agricultural income significantly reduce the probability of becoming
poor, the number of dependants and education of female members has an
opposite effect in Bangladesh. Benson et al. (2005) noted the positive
influence of education in reducing poverty in Malawi but highlighted that
the relationship is somewhat more complex than generally understood.
They emphasized increasing access to district level services to address
poverty. In contrast, Anyanwu (2005) noted that household size, primary
or lower level of education and rural occupation are positively associated
with poverty in Nigeria. He also noted feminization of poverty in Nigeria
and differential influence of geographic location on poverty. Wodon
(2000) noted that education, demographics, land ownership, occupation,
and geographic location, all affect poverty in Bangladesh. He further
noted that education influences inequality in urban areas while land
influences inequality in rural areas. Ravallion and Wodon (1999) also
noted that education and regional factors exert significant influence on
poverty in Bangladesh.
Micro-determinants of Income Inequality and Consumption in Rural Bangladesh 111
Methodology
(1)
with the relation
Micro-determinants of Income Inequality and Consumption in Rural Bangladesh 113
(2)
with the relation
(3)
with pi’s and wfi’s following m1≤m2≤…≤mn.
Substitution of equation 3 in 1 provides the decomposition of Gini
114 Journal of Poverty Alleviation and International Development
coefficient as:
(4)
with the relation
(5)
where, gf = is termed as relative concentration coefficient.
wfgf = share of component f in the Gini coefficient G.
An income component is said to be inequality increasing if its gf>1.
The implication is that if total income remains unchanged, the increase in
the share of a single component will result in an increase in overall
income inequality and vice-versa. In this decomposition method the
relative contribution of an income component to the Gini coefficient will
depend on its share in total income wf as well as on the value of gf.
households or region?
We have used “welfare ratios” to measure consumption defined as
the household’s per capita consumption normalized by the appropriate
regional poverty line so that differences in costs of living between
regions are taken into account (Wodon 2000). A welfare ratio equal to
one indicates that the household has consumption at the level of the
poverty line. In other words, if the welfare ratio is below unity, then the
household is deemed to be poor. In the conventional measure, binary
variables are used to define the poor, which takes the value of 1 for
households whose income falls below the poverty line expenditure and 0
otherwise. Such a measure cannot take into account how far a household
is below the poverty line expenditure. Our measure is providing a
continuous measure of the extent of poverty of the household relative to
the poverty line expenditure. A value above unity implies that the
household is above the poverty line and shows the extent to which it is
above the poverty line expenditure.
Following standard practice, we use the semi-log specification
since per capita consumption/welfare ratio (the dependent variable) is
not normally distributed (Wodon 2000). The following regression model
is specified:
(6)
The dependent variable is the log welfare ratios, i.e., log of nominal
per capita consumption divided by the poverty line of the area in which
the household lives (Wodon 2000). The Xi is the vector of regressors, β
is the vector of parameters to be estimated, and µi is the error term.
STATA V10 software is used to estimate the model (StataCorp 2010).
Data
Table 1.
Structure of Annual Total Income (BDT) Per Household
Source of income Share of component incomes to total income by region (%)
Jamalpur Jessore Comilla All regions
Total agricultural income 84.3 73.3 50.2 72.3
Crops 53.3 44.7 34.6 45.9
Traditional rice 3.9 0.3 3.2 2.6
Modern rice 44.5 26.6 22.6 33.3
Modern wheat 0.6 1.9 2.8 1.6
Jute 0.8 4.8 1.4 2.2
Potato 0.9 0.3 2.9 1.2
Pulses 0.0 3.9 0.2 1.3
Oilseeds 0.1 1.5 1.0 0.8
Spices 2.2 0.1 0.6 1.1
Vegetables 0.3 3.6 0.0 1.3
Cotton 0.0 1.6 0.0 0.5
Livestock 14.9 17.3 13.4 15.3
Fisheries 5.5 5.1 1.1 4.3
Lease 10.6 6.2 1.1 6.8
Total non-agricultural income 15.7 26.7 49.8 27.7
Wage 4.6 3.7 8.6 5.3
Business and other 11.1 23.0 41.2 22.4
Total family income 100.0 100.0 100.0 100.0
(31,581) (39,064) (25,314) (31,571)
Note. Figures in parentheses represent total income per household. Exchange rate USD 1.00 =
BDT 81.86 (Bangladesh Bank 2012). Source is Field Survey, 1997.
available food items that attain the recommended nutrition level of 2,112
kcal and 58 grams of protein per capita per day proposed by Mian (1978)
is utilized. In addition, expenditure on non-durable goods and/or
non-food allowance is estimated at 30 percent of the food poverty line (a
standard practice in the context of Bangladesh, e.g., Hossain (1989),
Ahmed and Hossain (1990). The region-specific poverty line
expenditures are different across regions with an overall estimate of BDT
5,409 per capita per year (see Table 2).
Consumption: Consumption expenditure was constructed using the
following procedure. First, quantities of food items consumed (both
purchased and home supplied) during seven days prior to the date of
interview were converted into values using market prices within the
village and then multiplied by 52 weeks to compute annual expenditure
on food. Next, monthly expenditure on durable goods, such as,
dress/clothing, education, transportation and debt servicing were
collected and multiplied by 12 months to compute annual expenditure.
Finally, annual expenditure on investment, maintenance of properties,
social and religious works was also collected. All these consumption
expenditure items were summed and then divided by household size to
obtain total nominal consumption expenditure per capita per year. The
region-specific actual consumption expenditure, thus constructed, are
significantly different across regions (F-statistic = 9.83; p<0.01) with an
overall estimate of BDT 6,068.6 per capita per year (see lower part of
Table 2).
Micro-determinants of Income Inequality and Consumption in Rural Bangladesh 119
Table 2.
Poverty Line Expenditure Required to Fulfill Nutritional and Other
Requirements
Food item Qty. (gm) of food Cost of attaining the optimal diet evaluated at
included in optimal region-specific retail market prices (BDT)
diet Jamalpur Jessore Comilla All regions
Rice 432.6 4.90 4.36 4.46 4.62
Wheat 58.3 0.64 0.58 0.64 0.62
Potato 36.7 0.15 0.14 0.15 0.14
Lentil 25.0 0.53 0.54 0.53 0.53
Fish 38.3 2.11 2.43 2.24 2.24
Meat 1.7 0.11 0.13 0.11 0.12
Milk 31.1 0.48 0.43 0.53 0.50
Dry milk 2.5 0.55 0.55 0.55 0.55
Sugar 27.2 0.70 0.70 0.70 0.70
Oil 12.2 0.70 0.69 0.63 0.68
Onion 8.5 0.09 0.07 0.07 0.08
Non-leafy vege. 86.8 0.38 0.58 0.52 0.53
Leafy vegetable 20.0 0.09 0.09 0.10 0.09
Cost of food per capita per day 11.43 11.29 11.23 11.40
Annual cost of food 4,172.0 4,120.9 4,099.0 4,161.0
Annual cost of non-food items 1,251.6 1,236.3 1,229.7 1,248.3
Poverty line expenditure per year per 5,423.6 5,357.2 5,328.7 5,409.3
capita
Actual estimated consumption 6,453.6 6,648.6 5,050.3 6,068.6
expenditure per year per capita
Welfare ratios (i.e., consumption 1.21 1.24 0.94 1.14
expenditure /poverty line expenditure)
Note. Exchange rate USD 1.00 = BDT 81.86 (Bangladesh Bank 2012). Values are extended from
Rahman (2009).
Results
1 For details of the construction procedure of the soil fertility index, see
Rahman (1999).
2 For details of the construction procedure of the infrastructure index, see
Rahman (1999) and Ahmed and Hossain (1990).
122 Journal of Poverty Alleviation and International Development
Table 3.
Measures of Income Inequality and Its Sources
Income Per capita Share in total Gini Concentration Contribution Relative Inequality
income income coefficient ratio to total Gini concentration weight
components % ratio %
mf wf G and Gf Cf wfCf gf=Cf/G wfgf
Comilla region
MV technology 1003.5 23.9 0.512 0.156 0.037 0.340 8.1
Other crop 413.7 09.8 0.757 0.409 0.040 0.889 8.7
Non-crop agri. 658.0 15.7 0.513 0.278 0.044 0.604 9.5
Non-agriculture 2129.2 50.6 0.750 0.670 0.339 1.457 73.8
Total income 4204.4 100.0 0.460 0.460 100.0
Jamalpur region
MV technology 2837.5 45.4 0.464 0.351 0.159 0.887 40.2
Other crop 442.3 07.1 0.746 0.329 0.023 0.829 5.9
Non-crop agri. 2030.0 32.4 0.599 0.463 0.150 1.167 37.9
Non-agriculture 946.8 15.1 0.820 0.425 0.064 1.075 16.3
Total income 6256.6 100.0 0.395 0.395 100.0
Jessore region
MV technology 1761.6 27.6 0.514 0.353 0.097 0.873 24.1
Other crop 950.8 14.9 0.646 0.457 0.068 1.131 16.8
Non-crop agri. 1835.8 28.8 0.562 0.398 0.114 0.986 28.3
Non-agriculture 1837.2 28.8 0.662 0.431 0.124 1.066 30.7
Total income 6385.4 100.0 0.404 0.404 100.0
All regions
MV technology 1990.1 35.2 0.534 0.354 0.125 0.817 28.8
Other crop 564.9 10.0 0.737 0.442 0.044 1.019 10.2
Non-crop agri. 1554.0 27.5 0.617 0.459 0.126 1.060 29.1
Non-agriculture 1544.0 27.3 0.757 0.507 0.139 1.170 32.0
Total income 5653.05 100.0 0.433 0.433 100.0
only provide direction of the influence but not the correct magnitude of
influence. Therefore, to obtain a measure of change in
consumption/welfare with respect to changes in the characteristics
variables, consumption/welfare elasticities at the sample means are
estimated and reported in Table 5.
In general, studies investigating the influence of land resources,
whether measured as owned or simply land under cultivation, find a
positive effect on income levels or input demand. In this study, two
variables are used to represent land resources. Intuitively, the major land
factor determining income levels and hence consumption will be land
owned. Results reveal that land ownership significantly increases
consumption/welfare and is the most dominant variable consistent with
our expectation. The elasticity value is estimated at 0.14 implying that a
one percent increase in land owned per capita will increase consumption
by 0.14 percent. Wodon (2000) also reported significant influence of land
ownership on consumption in rural areas. Although farm size has no
influence on consumption, farm capital assets significantly influence
consumption, again consistent with expectation. The implication is that
wealth, measured in terms of land ownership and/or capital assets,
significantly enhances consumption. This is expected in a land scarce
country like Bangladesh where land is a major source of wealth.
Modern irrigation, a major pre-requisite and input for modern
agricultural technology, also significantly increases consumption as
expected and is the second strongest determinant amongst the
socio-economic factors after land ownership, with an elasticity value of
0.07. This is because irrigation opens up opportunities to adopt modern
rice technology which provides significantly higher yields than
traditional rice, and therefore enhances consumption.
Return to education of the head on consumption is also significant
and is the third most dominant variable with an elasticity value of 0.04.
The coefficient on the maximum level of education of any member in the
household is also positive and significant at the 15 percent level. Wodon
(2000) also reported significant returns to education on consumption.
126 Journal of Poverty Alleviation and International Development
Similarly, Achia et al. (2010) and Benson et al. (2005) noted a significant
influence of education on reducing poverty. The implication is that
education for members of the household is positively associated with
enhancing consumption. The combined influence of these two education
variables is 0.09 which means that a one percent increase in educational
attainment at the household level will increase consumption by 0.09
percent.
Non-agricultural income source also significantly increases
consumption as expected and is consistent with the literature. A one
percent increase in non-agricultural income will increase consumption
by 0.03 percent. Rahman (2009) also noted a significant poverty
reduction influence for non-agricultural income.
Tenants have a significantly lower level of consumption.
Bangladesh is an economy where functionally landless households
account for over 50 percent of agricultural production units. Since the
land rental market is not very effective, generation of income through
farming is difficult which ultimately affects consumption adversely.
Rahman (2009) also noted that tenants are more likely to be poor.
The number of dependents in the household significantly reduces
consumption and the effect is highest with an elasticity value of –0.28. A
higher number of dependents exerts pressure on the household with
respect to consumption of goods and services which are to be provided
by fewer earners. The finding is consistent with those reported in the
literature (e.g., Anwanyu 2005).
The regional/location factor also exerts significant influence on
consumption. There is a pronounced positive influence of rural
infrastructure on consumption. Consumption is significantly higher in
developed regions. The elasticity value indicates that a one percent
increase in the index of rural infrastructure will increase consumption by
0.13 percent. In general, the developmental effect of infrastructure is
indirect and complex (Ahmed & Hossain 1990), although its influence
on poverty and inequality is emphasized in the literature. For example,
Benson et al. (2005) and Anyanwu (2005) recommended improving
Micro-determinants of Income Inequality and Consumption in Rural Bangladesh 127
Table 4.
Microdeterminants of Income Inequality
Variable list Coefficient Robust z-values
standard errors
Constant 0.348* 0.217 1.65
Socio-economic factors
Per capita land owned 1.208*** 0.192 6.30
Farm operation size 0.001 0.024 0.01
Farm capital assets 0.002* 0.000 1.67
Herfindahl index of crop diversity -0.035 0.075 -0.49
Irrigation 0.108* 0.067 1.65
Tenants -0.117** 0.053 -2.21
Share of non-agricultural income 0.123** 0.059 2.07
Dependents in the household -0.070*** 0.010 -6.90
Education level of household head 0.010* 0.005 1.82
Highest education of male member in the 0.009 0.006 1.47
household
Age of the head 0.001 0.001 0.84
Village level factors
Index of infrastructure underdevelopment -0.004*** 0.001 -2.60
Index of soil fertility -0.117 0.136 -0.86
Comilla region -0.175*** 0.047 -3.70
Jessore region -0.043 0.071 -0.61
Model diagnostic
Adjusted R2 0.45
F-statistic (15,390df) 25.98***
H0: No influence of socio-economic factors on 25.27***
consumption/welfare (F-statistic (8,390df)
H0: No influence of spatial/geographic factors on 6.45***
consumption/welfare (F-statistic (4,390df)
Number of observations 406
*** = significant at 1 percent level (p<0.01); ** = significant at 5 percent level (p<0.05); * =
significant at 10 percent level (p<0.10).
128 Journal of Poverty Alleviation and International Development
Table 5.
Consumption/Welfare Elasticities
Variable list Elasticity estimates
Socio-economic factors
Per capita land owned 0.135**
Farm operation size 0.001
Farm capital assets 0.012*
Herfindahl index of crop diversity -0.021
Irrigation 0.067*
Tenants -0.017**
Share of non-agricultural income 0.027**
Dependents in the household -0.279***
Education level of household head 0.037*
Highest education of male member in the household 0.054
Age of the head 0.047
Regional/spatial factors
Index of infrastructure underdevelopment -0.132***
Index of soil fertility -0.196
Comilla region -0.054***
Jessore region -0.011
*** = significant at 1 percent level (p<0.01); ** = significant at 5 percent level (p<0.05); * =
significant at 10 percent level (p<0.10).
References
Appendix
Derivation of Income