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Composite Index of Inclusive Growth in Sub- Saharan Africa: The Inclusion of the Informal Sector

This paper aims to provide a composite index of inclusive growth in 32 sub-Saharan African countries between 1995 and 2014 by taking into account the importance of the informal sector. Following the principal component analysis methods, we find specifically that except for countries such as Djibouti, Burkina Faso, Mauritius, Nigeria and Zimbabwe, inclusive growth has trended upward over the study period. This trend is non-linear and is characterized by two sub periods. From 1995 to 2005, the composite index of inclusive growth is essentially negative. On the other hand, positive growth in value is recorded over the second sub-period from 2005 to 2014. Overall and on average, these countries have experienced inclusive growth. Moreover, we also note that in countries such as Burkina Faso, Mauritius and Nigeria, on the side-lines of the informal sector inclusive growth has a negative trend. However, when we integrate the informal sector, the trend of inclusive growth changes sign and becomes positive.


INTRODUCTION
Since the 1960s, the pursuit of well-being during the development process is a major challenge that has seen endless attempts at solutions in developing countries. Initially, the paradox between high performance in terms of economic growth and high prevalence of inequality was a response in the event of the inverted "U" developed by Kuznets [1] 1 . Although Barro [2] confirmed empirically this hypothesis for several countries, the experience of Asian countries 2 did not support it [3]. An alternative framework emphasizing the priority of the efficiency of economic growth on income distribution was considered after 1960. Unfortunately, it does not explains much the persistence of inequalities in the process of economic growth [4] 3 . Subsequently, the idea of improving the monetary conditions of the poor promote propoor growth theories in the 1980s. However, the ambiguity of the empirical results of this growth mechanism stimulates new research on inclusive growth policies 4 . This new vision promoted by international institutions requires that we go beyond the policy of intensification of growth and pro-poor policies. The analysis should now overlook the only advantages related to high level of gross domestic product. Indeed, some economies have experienced strong performance in production without a significant impact on poverty, inequality and welfare. If inclusive growth appears as a panacea for development, it should be noted that 1 According to Kuznets [1] the first periods of economic growth is usually accompanied by rising inequality. These should however decrease as and as growth becomes sustainable. 2 African Development Bank [5]. 3 According to them, given the fact that the proportion of the rich on the wealth creation process in an economy is larger than that of the poor, an acceleration of growth would benefit benefit the rich more than the poor. 4 Indeed, in Thailand the work Kakwani and Pernia [6] between 1990 and 1998 showed that the reduction of poverty in the country has been accompanied by rising inequality. In Europe, studies conducted between 1980 and 2000 show that growth was pro-poor in France, Spain and Italy, anti-poor Germany [7]. Ironically the same period, Germany recorded a better solvency in national accounts than other countries. In Tunisia, the same study has allowed to see a significant reduction in poverty despite the fact that growth was not propoor [8]. In Israel, we see that between 1995 and 2010, growth was pro-rich despite the reduction of poverty [9]. In South Africa and Mauritania over the same period, growth was anti-poor and accompanied by rising inequality. Even more, a study [6] in five East African countries serves to emphasize that the reduction of poverty and inequality in these countries do not always come from pro-poor growth policies.
this notion divides scientific opinion on both its definition and its measurement.
This paper attempts to address this issue by providing a composite index of inclusive growth in sub-Saharan Africa with the particularity of taking into account the informal sector which was not measurable. The indicator we propose measures the inclusive growth level of 32 sub-Saharan countries 5 between 1995 and 2014. We rely on the principal component analysis. Based on this sample, we compute two composite index of inclusive growth. The first ignores the informal sector while the second includes the informal sector. However, for some data unavailability reasons the second index is calculated only on a set of 29 countries.
Our results show that with the exception of countries such as Djibouti, Burkina Faso, Mauritius, Nigeria and Zimbabwe inclusive growth has trended upward over the study period. This trend is non-linear and characterized by two sub-periods. From 1995 to 2005, the composite index of inclusive growth is essentially negative. During the second sub-period covering 2005 to 2014, inclusive recorded positive growth in value. As a general result and on average, these countries have experienced inclusive growth. Furthermore, in countries such as Burkina Faso, Mauritius and Nigeria, on the sidelines of the informal sector inclusive growth has a negative trend. When integrating the informal sector, the trend this inclusive growth becomes positive.
The reminder of the paper is structured as follows. The second section outlines our choice of indicators in the light of literature; the third presents the methodology for the construction of our index.

LITERATURE REVIEW
Today, despite the consensus on the usefulness of inclusive growth for a country, the definition and measurement of this concept divide economists. According to Kakwani and Pernia [5], inclusive growth must be pro-poor growth strategy bonus via the overall well-being. This bonus must pass through full employment [10]. It must include all social layers in the production process [11]. The aim is to sustainably reduce unemployment in an identifiable part by individuals with equal opportunity to have access to economic opportunities [12]. Ali and Son [3] also recommended that this strategy is the poor social strata to counteract income inequality. Growth would therefore be called inclusive when it addresses not only the explanatory factors of development, but also to the equitable distribution of the fruits of growth. It is not propoor growth if limited only to the increase in the purchasing power of the poor population and reducing inequalities. It shall promote the mastery of participation strategies in the production and distribution of the final product [13].
Depending on the institutions and some posteriori, the definition of inclusive growth also depends on the context and level of development of each economy. For UNDP [14], the inclusiveness of growth should be realized not only by the full participation of all people in the growth process, but also equality in sharing. The World Bank, meanwhile defined inclusive growth as equal access to resources and markets with a regulatory environment beneficial to all (OECD [15]. This definition further promotes micro and macroeconomic approach with a focus on the pace and pattern of economic growth [16]. Regarding the Asian Bank and the African Development Bank (AfDB) 6 , inclusive growth boils down to reducing inequalities through increased opportunities for low-purchasing power categories to have access to health, education, social integration and nutrition. This is an approach that emphasizes the mastery of the process and results of economic growth [15].
All these definitions show how to federate the design of inclusive growth can be complex. To try to overcome this difficulty, Klasen [17] considers inclusive growth as a process having a dual approach. The first approach revises a restricted nature of non-monetary dimension, and the second approach is to revise a non-monetary dimension of a global nature. Non-monetary dimension restricted nature is that which comes down to a bonus strategy for pro-poor growth 7  In summary, inclusive growth is similar to a process of creation of wealth that one hand is characterized by promoting social equity in the population and secondly, promotion of balances on economic, political, social, spatial and environmental. Despite this clarification, it must be said that the empirical evidence on the extent of this so-called inclusive growth in Sub-Saharan Africa remains mixed with neglect of the importance of the informal sector which also occupies a large part of the population and captures most part of their savings.
On the first steps to Ianchovichina and Lundstrom [22] on Zambian economy analyse inclusive growth through proxies of well-being determined by a weighting factor prices showed that the country did not experience inclusive growth. Subsequently, the work of the African Development Bank (2012, 2013, 2015) on a sample of 46 countries in sub-Saharan Africa and the Maghreb have used composite indicators. These indicators were determined by weighting variables such as: Adjusted inequalities, gross domestic product per capita, diversification of economies, the level of infrastructure, governance indicators, health, education, women's employment and elasticity of growth [23]. The results of these studies have also shown that inclusive growth was a mixed reality in these countries. Also in the same vein, the United Nations Development Program [24,25] sponsored a number of works in some countries of the continent. But the most interesting study is that of Ramos et al. [26]. They combined the term pro-poor growth with the concept of inclusive growth by using the benefits associated with the participation in the growth process. Finally, Hakimian [21] provides a composite indicator of inclusive growth that combines 14 variables but the most interesting study is that of Ramos et al. [26]. She combined the term propoor growth of the concept of inclusive growth by using the benefits associated with participation in the growth process. Finally, Hakimian [21] provides a composite indicator of inclusive growth that combines 14 variables But the most interesting study is that of Ramos et al. [26]. She combined the term pro-poor growth of the concept of inclusive growth by using the benefits associated with participation in the growth process. Finally, Hakimian [21] provides a composite indicator of inclusive growth that combines 14 variables 9 . Applied to a sample of countries in North Africa and the Middle East, the level of inclusive growth in these countries compared to a number of developing countries is still unsatisfactory with the exception of Tunisia. Given the influence that this "pejorative" variable informal economy can have on an inclusive growth process, we integrate in the construction of our inclusive growth index. Other variables such as availability of arable lands, export diversification, access to electricity, emissions of carbon dioxide and life expectancy will be included as additional variables. These do not participate in the construction of the index. Descriptive statistics of all the variables that we have just presented is found in the Table 1.

RESULTS AND DISCUSSION
The composite index of inclusive growth is made of 29 sub-Saharan countries over the period from 1999 to 2013 (Appendix 3). Some countries are excluded due to the unavailability of data on the informal sector.

SENSITIVITY AND ROBUSTNESS TESTS
Using the principal component analysis, a composite indicator can generate two bias. The first potential bias based on the fact that building the index taking into account only one factor axis may not be significant. A factorial axis can explain more than 70% of the total variance of the sample while some areas have higher scores than or equal to 100 / P. Therefore, the construction of the index in this base may promote the non-consideration of the effect of a variable represented by another factor axis. This is the case for countries such as Benin, Botswana, Burkina Faso, Cape Verde, Ivory Coast, Lesotho. Second, neglect or integration of a variable in the construction of the index can lead us to another trend of the overall sample. To address the first limit, we used the method of . They propose to make weights of the remaining eigenvectors to maximize the explanatory power of the total variance of the sample by a number of factor axes. As for the second term, we built another composite index on the side-lines of the informal sector in order to verify the relevance of this variable in the sample.
We carry out the method of Mikhail et al.
[38] by retaining the first three factorial axes. These enable us to explain over 90% of the total variance of the sample. Only Lesotho records a total score of 87%. The results of our calculations are shown in graphs of Appendix 1. It clearly shows that both indices have the same trend and is moving in the same direction. In the first subperiod, the countries in our sample have a negative inclusive growth. While in the second sub-period, these countries have a positive inclusive growth.
As second limit, the construction of another index on the margin of the informal sector using the principal component analysis is substantially the same as that constructed by the method of Mikhail et al. [38]. These results are demonstrated by the different curves by countries in our sample (Appendix 2).
However, comparing the two approaches shows that inclusive growth indices have a interesting result. Indeed, the analysis of these graphs shows that in countries such as Burkina Faso, Mauritius and Nigeria, on the side-lines of the informal sector inclusive growth has a negative trend. But once you integrate the informal sector, the trend of this inclusive growth becomes positive. This result raises a question about the true determinants of the interrelationship between the informal sector and inclusive growth.
Finally, we also test the sensitivity of our composite index with respect to the explanatory variables in our sample. Table 2 shows that inclusive growth is negatively correlated with income inequality and positively correlated with other variables. However, the positive correlation of the informal sector inclusive growth can be justified by the fact that people who work in the informal sector can achieve significant benefits allowing them for example to offer goods such as health, education and drinking water.

CONCLUSION
The aim of this article is to build and provide a composite index of inclusive growth in sub-Saharan Africa. Indeed, despite the existence of a multitude of composite index of inclusive growth, none of which to the best of our knowledge has integrated the informal sector.