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Mapping Indicators of Poverty in
West Africa
1. Background
GRID-Arendal was approached
by TAC for assistance in the production of reliable statistical and
cartographic products on poverty and land use potential. These activities
are integrated into an on-going collaborative project between UNEP and
the CGIAR, 'Use of GIS in Agricultural Research'.
The poverty mapping activities
have been conducted in a relatively short period (March - May 1997),
starting with a small workshop discussing scope, data sources and outputs
of the study. Invaluable inputs to these preliminary activities were
given by Jake Brunner of the World Resources Institute and Uwe Deichmann
from the UN Statistical Division. GIS analysis, interpretation and presentation
activities were carried out at GRID-Arendal by the authors of the study.
2. Objectives
Generation of reliable
statistical and cartographic products to communicate the relationship
between rural poverty and land use potential in West Africa, in order
to provide information to ensure optimal use of research investment.
Furthermore, the project served
as a pilot study to investigate an appropriate approach to identify
the location of poor people on a global basis with a reasonable investment
of time and resources.
3. Approach
Measuring poverty requires
taking into account a variety of factors. A standard indicator frequently
used is the pure economic value 'GNP per capita'. Using this attribute
makes sense if the study is to be comparable at a global level. However,
GNP data is not available universally at the desired accuracy. We therefore
chose to represent poverty - following the example of a WRI study in
progress entitled 'Human Development versus Aridity in West Africa'
- using the indicator variables of the Human Development Index (HDI)
(UNDP, 1996)1.
The actual data comes from the Health and Demographic Survey (HDS)1.
Because none of the HDI indicators
are explicitly captured in that survey, surrogate variables are used
from the DHS data to infer poverty levels2.
The four surrogate variables used in this study are: Child Mortality,
Adult Female Literacy, Primary School Enrolment, and Children with Stunted
Growth. These data exist for 2263 sample points within West Africa3.
In a second step, we excluded all urban samples to get a better idea
of the situation of the rural poor (1113 samples).
As with 'poverty', the term
'marginal land', in terms of potential for crop production, has to be
approximated in a most reasonable way, since there is no obvious, general
and applied definition of it. To detect possible influences of spatial
factors on the degree of human development/poverty, the data was combined
with 4 different approximations of 'Marginal Land'4.
Those can be grouped in two categories:
- Biophysical:
- Agroclimatic Zones
- Land Degradation
- Socio-economic:
- Population Density
- Accessibility to Infrastructure
and Roads
The first three factors were analysed for all West-African countries,
whereas the accessibility data was only available for Burkina Faso and
Mali. The accessibility data was developed under the project. The definitions
of the above factors can be found in the appendix.
When representing the data
in maps and graphics, we chose to display each surrogate variable for
human development separately rather than combine them in the suggested
HDI, to keep the process more transparent.
The correlation of the HDI
surrogates with the marginal condition factors was carried out using
a GIS. GIS and statistical processing included point and polygon overlay
analysis, using Arc/Info and Arc/View software. For each HDI sample
point, a geographically referenced value was extracted from each thematic
layer. An average and standard error was then calculated for each surrogate
variable by thematic classes.
4. Results
The presentation of results
consists of:
- a map for each indicator for human
development (representing an approximation of poverty) by thematic
class,
- the corresponding graphs displaying
the HDI indicators in correlation with the background data, and
- a general interpretation
of the results.
Notes:
- See appendix
2 and 3 for detailed definition
- Although poverty
levels were not measured directly, the terms 'Human Development' and
'Poverty' are used interchangeably in the text.
- The Human Development
Survey was conducted in the following countries: Burkina Faso, Cameroon,
Central African Republic, Cote d'Ivoire, Ghana, Liberia, Libya, Mali,
Niger, Nigeria, Togo, Zaïre.
- We explicitly avoid
giving absolute indications of what is more marginal. This can vary
from factor to factor and is therefore left for interpretation by
the reader.