Soc Indic Res https://doi.org/10.1007/s11205-018-1867-6 Inequality Between Whom? Patterns, Trends, and Implications of Horizontal Inequality in the Philippines 1 2 2 2 Omar Shahabudin McDoom · Celia Reyes · Christian Mina · Ronina Asis Accepted: 18 February 2018 © UNU-WIDER 2018, corrected publication May 2018 Abstract An overall decline in inequality within a country, when assessed using national- level measures, can evidently obscure important variation in inequality at the subnational level. However, social planners face a choice, whose importance we argue is often under- estimated, in deciding the appropriate spatial and social boundaries along which inequality should be measured at the local level. We illustrate the consequential nature of this choice by examining a historically unequal country that has experienced a recent overall decline in inequality at the national level. Drawing on census micro-data, we show the Philippines made impressive progress in reducing disparities in education and access to basic public services between 2000 and 2010. This change, however, appears less positive when ine- quality is measured at the subnational level using spatial and social boundaries selected for their socio-political significance in the Philippines context. Specifically, using measures of total, within-group and between-group inequality, we find important differences within and between three salient ethno-religious groupings—Muslims, indigenous persons, and everyone else—as well as within and between three major island groupings, Mindanao, Visayas, and Luzon. We consider the implication of one of these differences—variation in between-group inequality—by examining its correlation with social and political instability The original version of this article was revised due to a retrospective Open Access order. * Omar Shahabudin McDoom firstname.lastname@example.org Celia Reyes email@example.com Christian Mina firstname.lastname@example.org Ronina Asis email@example.com London School of Economics, London, UK Philippine Institute for Development Studies, Quezon, Philippines 1 3 O. S. McDoom et al. at the subnational level. Our findings underscore the importance of examining inequality at appropriate localized levels of analysis and, specifically, selecting carefully the spatial and social boundaries along which it should be measured. Keywords Horizontal inequality · Ethnic group · Indigenous people · Violent conflict · Philippines · Mindanao JEL Classification J15 · I24 · D63 · Z13 1 Introduction Although inequality has become one of the defining political issues of the early twenty-first century—its reduction has become United Nations Sustainable Development Goal 10— global income inequality has in fact been in decline for more than three decades. Between 1975 and 2010, the Gini coefficient, perhaps the most well-known measure of relative ine- quality, moved from 0.739 to 0.631, based on the most comprehensive data on income ine- quality available globally (Niño-Zarazúa et al. 2017). Analysis at such a highly-aggregated level obviously obscures important differences between regions and countries. Inequality trends in North America differ dramatically from those in East Asia and the Pacific, for instance. Similarly, inequality patterns in China are starkly different from those in Japan. These differences are not only of normative concern; they may also have observable con- sequences. The “Occupy Movement” for example, originated in 2011 in New York City, arguably the world’s financial center of gravity, and reportedly expanded to inspire protests in over 900 cities across 82 countries all around the world (Adam 2011). In this article, we take the level of analysis one step lower and explore the significance of inequality patterns at the subnational level. National-level analysis can conceal meaning- ful subnational variation in the same manner as global and regional-level data may mask important country-level differences. The Philippines is a rising lower middle-income econ- omy, noted for historically high levels of inequality (Kondo 2014), but whose income ine- quality has followed the global downward trend over the last two decades. From a peak of 0.5183 in 1997, the year of the Asian Financial Crisis, the Philippines’ Gini coefficient has since monotonically declined from 0.5045 in 2000 to 0.4714 in 2012 (Reyes et al. 2012). While such a redistribution of income may seem cause for celebration for advocates of social justice, we urge caution. We explore subnational patterns and trends in inequality within and across spatial and social boundaries in the Philippines. There has been scant research on ine- quality between socially-salient groups in particular in the Philippines and the country’s social and geographic complexity presents a useful opportunity to illustrate the value of examining inequality at more localized levels of analysis. Our findings highlight the risks of reliance on measures aggregated at levels that may obscure inequality’s consequences. In analyzing subnational inequality we make two important conceptual choices. First, we focus on inequality of opportunity rather than inequality of outcome given the greater normative significance attached to disparities in life chances. Specifically, instead of income or wealth inequality, we examine indicators of education and access to basic services. Second, we measure inequality along subnational spatial and social boundaries purposely defined and selected for their socio-political significance. The consensus on the socially-constructed nature of ethnic identities (Chandra 2006) underscores the importance of considering carefully how groups should be categorized when measuring between-group disparities. Our findings confirm not only that there is substantial subnational variation 1 3 Inequality Between Whom? Patterns, Trends, and Implications… between regions and social groups in inequality levels and trends but, furthermore, that these differences are cause for concern in the Philippines context. Specifically, we examine inequality levels and trends first between and within the Philip- pines’ three major island groupings each with distinct politico-historical trajectories: Mind- anao, Visayas, and Luzon; and second, between and within three socially and politically sali- ent ethno-religious blocs: Muslims, indigenous persons (who are not Muslims), and everyone else i.e. those who are neither Muslim nor an indigenous person. Our headline findings indi- cate that contrary to the overall favorable picture of inequality’s decline at the national-level between 2000 and 2010, there are stark subnational differences between regions and ethno- religious groups in levels and trends. More particularly, first, Mindanao has, by far, the high- est levels of overall, within-group, and between-group inequality of the three island regions. Second, overall inequality levels improved in all three regions but much more significantly in Luzon and Visayas than in Mindanao, thus widening the gap between them. Third, between- group (horizontal) inequality improved in Luzon and to a lesser extent Visayas, but Mindanao became more unequal in almost all measured dimensions principally due to an increase in the gap between Muslims and indigenous persons on the one hand and everyone else on the other. Fourth, although Muslims and indigenous persons have the highest levels of within- group inequality and lowest socio-economic scores at the national level, at the subnational level their situations vary with island region. Within-group inequality is high among Muslims in Mindanao and indigenous persons in Luzon where both groups are also at the bottom of the socio-economic hierarchy, but low among Muslims in Luzon and indigenous persons in Visayas respectively where their socio-economic status is also better. We suggest these subnational differences, as well as others we enumerate later in the article, have observable consequences as well as implications for policy-makers in the Phil- ippines. We illustrate the importance of these implications by considering one potential consequence of one of these differences: the impact of differences in levels of between- group inequality on the country’s social and political stability. Our analysis suggests a strong association between horizontal inequality and stability. Specifically, Mindanao, which has the highest and also a worsening level of inequality between the three ethno- religious groups, also has the highest incidence of events indicative of social and political instability among the three regions. Our analysis underscores the importance of further work on such subnational associations in the Philippines. The article proceeds as follows. Section 2 explains the choices we make in conceptualizing inequality. Section 3 introduces the Philippines to the reader and reviews existing work on ine- quality in the country. Section 4 then describes the data and methods employed. Section 5 pre- sents our findings, distinguishing between national and subnational-level results, and examining the association between horizontal inequality and socio-political stability. Section 6 concludes. 2 Conceptualizing Inequality The rising importance of inequality in global political discourse at the start of the twenty- first century has spurred interest in the debate over how to conceptualize inequality. Two questions have received considerable attention in this discussion. Inequality of what? And inequality between whom? In this article, we examine, first, inequality of opportunity rather than inequality of outcome and, second, inequality between socially salient groups rather than inequality between individuals or households. The latter concept is sometimes also referred to as horizontal inequality. We describe the theoretical logic advanced by each 1 3 O. S. McDoom et al. concept’s principal proponents for why inequality of opportunity and horizontal inequality are important, and why we chose to examine them, along with working definitions used in the article. The concept of inequality of opportunity has longstanding antecedents that reach back to Rawls’ (1971) theory of justice, Sen’s (1987) human capability approach, and Dworkin’s (1981) idea of equality of resources, inter alia. The core idea is the importance attached to individual responsibility for achievements. Roemer (1998), building on this work, defined equality of opportunity in terms of “advantages” and distinguished between advantages attributable to an individual’s “efforts” and advantages attributable to “circumstances” that are beyond her control. Equality of opportunity exists when advantages are attained inde- pendently of such circumstances. Inequality of opportunity then matters because it offends normative principles of social fairness. It is unfair to hold an individual responsible for an outcome that is beyond her power to influence. We focus then in the article on the features of a person’s environment that affect life chances but for which the person is not unequiv - ocally responsible. For these reasons, we examine inequality in education and access to basic services given their collective potential to shape life chances. Specifically, we look at years of schooling, literacy, and access to electricity, safe water, and sanitation. Table 1 provides technical definitions of these indicators. The concept of horizontal inequality, introduced and developed principally by Stew- art (2002) has importance for both normative and consequentialist reasons. Stewart and Langer (2006) defined it as “inequality among culturally defined (or constructed) groups, in contrast with vertical inequality (VI) which is inequality among households or indi- viduals”. Material differences between ethno-cultural groups that result, for instance, from historical disadvantages or contemporary prejudice and discrimination, raise normative concerns for fairness in society. But horizontal inequality is also believed to be important because it has observable adverse consequences. An ever-expanding body of empirical work has documented horizontal or between-group inequality’s links with poor social inte- gration (McDoom 2018), public goods under-provision (Baldwin and Huber 2010), demo- cratic instability (Huber and Suryanarayan 2015), economic under-development (Stewart 2002), and with civil war and social conflict more generally (Cederman et al. 2013). Stewart’s definition of horizontal inequality also explicitly acknowledges the socially- constructed nature of ethno-cultural groups. We pay particular attention to this issue in operationalizing horizontal inequality as how best to define and categorize groups is not always obvious and the choice can be consequential (McDoom and Gisselquist 2016). Table 1 Definition of indicators analyzed Indicator Definition Schooling Years of schooling if individual is aged 25 and over Literacy 1 if an individual aged 10 and over is literate (or can both read and write a simple message); 0 if illiterate Access to safe water 1 if an individual belongs to a household having access to safe drinking water (or if main source of drinking water supply is either community water system, tubed/ piped well or bottled water); 0 otherwise Access to sanitation 1 if an individual belongs to a household having access to a sanitary toilet facility (or if type of toilet facility is either water-sealed sewer septic tank, other depository, or closed pit); 0 otherwise Access to electricity 1 if an individual belongs to a household having access to electricity; 0 otherwise 1 3 Inequality Between Whom? Patterns, Trends, and Implications… However, it is not only social boundaries that may be constructed. Spatial boundaries may also result from socio-historical processes. While formal spatial boundaries—for instance those that distinguish urban from rural areas or that define administrative regions—are commonly and conveniently employed in subnational analyses, we argue that these are not necessarily always the boundaries with the greatest salience if our objective is to under- stand inequality’s consequences. For this reason, we consider spatial boundaries whose resonance with individuals and communities derives from how they identify and compare themselves geographically. In the context of the Philippines, the distinct historical trajecto- ries behind the three major island groupings of Luzon, Visayas, and Mindanao suggest it may useful to explore inequality within and between them. 3 The Philippines and Inequality 3.1 Case Background The distinct politico-historical significance of the Philippines’ three major island groups reflects their distinct pre-colonial settlement patterns and subsequent colonial experiences. One critical juncture that helped shape these informal boundaries was the arrival of impe- rial Spain in the sixteenth century which concentrated its colonial resources first in Luzon and then in Visayas. Spanish conquest ensured Catholicism and an overarching Filipino identity would become dominant social forces in these two northern regions in marked contrast with Mindanao in the south, whose earlier contact with Islam in the fourteenth century, was central to resistance to Christianization and Filipinization (Majul 1988). This resistance would abate during the American colonial period (1898–1946) (Abinales 2010) and intensify in the post-colonial era (1946+) when an expanded resettlement program for migrants from Luzon and Visayas would exacerbate the dispossession and minoritization of Mindanao’s native population. This marginalization would help motivate several armed rebellions from within the Muslim Moro communities (McKenna 1998) which the Philip- pines central government, established in Luzon, has not fully resolved as of today. It is for these reasons that subnational inequality patterns between and within these three island groups are valuable to examine in the Philippines context. Demographically, the Philippines grew from 76.3 to 92.1 million individuals between 2000 and 2010. Broadly, more than half of these individuals are densely-concentrated in Luzon with nearly one quarter in Mindanao and one fifth in Visayas. The 2000 and 2010 Population Censuses, allowing self-identification, recorded 147 and 182 ethno-linguistic groups respectively as well as 93 and then 97 religious affiliations in the Philippines. The apparently significant increase in ethno-linguistic diversity recorded in just one decade underscores the constructed, fluid, and subjective nature of ethnic identity and the chal- lenge of measuring it and for this reason, we re-classified this social complexity into a smaller number of groupings whose socio-political salience had proven more resilient in the longue durée. This approach, focusing purposely on only politically and/or socially rel- evant groups, has been practised by a number of ethnic politics specialists interested in estimating the effects of ethnic diversity and divisions in societies (Posner 2004; Birnir et al. 2015; Wucherpfennig et al. 2011). We consequently re-grouped the population into Muslims, indigenous persons (who were not Muslim), and everyone else. The longstand- ing salience of Muslim identity in the Philippines context reflects the historic conflict and resistance to incorporation into the modern Filipino state by Mindanao’s Moro population. 1 3 O. S. McDoom et al. For indigenous communities, the socio-political significance of indigenous status is reflected in the institutions the modern Filipino state had established to protect their rights as well as the conflicts with competing private interests, particularly over ancestral lands and natural resources thereon, that these institutions then intensified. Both Muslims and indigenous persons (non-Muslim) are minority groupings and rep- resented approximately 5.5 and 8.6% of the overall Filipino population respectively in 2010. Muslims are overwhelmingly located in Mindanao where they represent nearly one fifth of its population and are concentrated principally in the Autonomous Region of Mus- lim Mindanao (ARMM). Indigenous persons, in contrast, are spread throughout all three regions with stronger concentrations in Luzon, primarily in the Cordillera Administrative Region (CAR), and Mindanao, primarily in upland and forest areas. Non-Muslim, non- indigenous persons represent an overall national majority, 86.0%, as well as a majority in all three island groups. They also have the overall highest socio-economic status of the three groupings. Educationally for instance, non-Muslim, non-indigenous persons had received an average of 9.1 years of schooling and 98.7% were literate in 2010. In con- trast, Muslims and indigenous persons had received 6.1 and 7.3 years of schooling and had 85.3 and 92.8% literacy respectively. This hierarchy holds at the national level for the other three developmental indicators—access to safe water, sanitation, and electricity—that we analyzed, though Muslims had a slight advantage over indigenous persons on the latter two dimensions. Table 2 summarizes descriptive statistics at the national and subnational levels for each of the three groups and on each of the 5 development indicators examined. It is worth noting that, although Muslims remain the most educationally-disadvantaged grouping, they recorded the strongest percentage increase in schooling and literacy levels between 2000 and 2010 of the three groups. Further research would help establish whether this could be attributed to efforts, beginning in 2004, to align the madrassahs, Islamic reli- gious schools, with the national educational system. 3.2 Inequality in the Philippines Despite the stark differences between these groupings, and the socio-political significance of them, there has been surprisingly little research on between-group inequality in the Phil- ippines. Much of the extant work examines national-level or spatial inequality between urban and rural areas or between different subnational administrative units. The focus has also been primarily on income or wealth inequality, and not inequality of opportunity. The findings are nonetheless worth reviewing here not least for their suggestions of inequality drivers in the Philippines context. It is widely-recognized that the Philippines has had historically high levels of income and wealth inequality by global and regional standards. Land inequality in particular has been analyzed as an influential initial condition that has shaped the country’s subsequent growth and poverty levels (Balisacan and Fuwa 2004). The origins of land inequality lie, in part, in the Spanish colonial conquest whose legacy includes the concentration of land in the hands of Filipinos of Spanish ancestry who in turn constitute an entrenched elite class generally opposed to land reform and who occupy a prominent position in the country’s politics and business (Sidel 1999; McCoy 2009). A significant body of research has also highlighted the large and growing spatial inequalities in the Philippines. The urban–rural gap in particular is significant. Research has suggested urbanization, specifically the grow - ing share of the population that lives in urban areas, accounts for the slight increase in national income inequality observed between 1991 and 2009 (an increase using Theil but 1 3 Inequality Between Whom? Patterns, Trends, and Implications… 1 3 Table 2 Descriptive statistics on ethno-religious groups in the Philippines in 2000 and 2010 Group size Group size (%) Schooling Literacy (%) Safe water (%) Sanitation (%) Electricity (%) (years) Philippines 2000 Muslims 3,036,228 4.39 5.5 73.8 44.4 74.8 51.3 Indigenous persons 5,641,657 8.16 6.7 84.9 62.1 51.4 40.8 Non-Muslims, Non-IPs 60,490,270 87.45 8.3 94.4 76.0 83.8 72.6 All groups 69,168,155 100 8.1 92.8 73.5 81.6 69.5 2010 Muslims 4,998,559 5.49 6.1 85.3 53.3 80.3 63.5 Indigenous persons 7,792,793 8.56 7.3 92.8 64.0 63.7 61.5 Non-Muslims, Non-IPs 78,220,933 85.95 9.1 98.7 81.7 90.9 86.9 All groups 91,012,285 100 8.8 97.6 78.6 88.5 83.5 Mindanao 2000 Muslims 2,905,761 18.04 5.3 73.0 43.1 68.2 36.7 Indigenous persons 1,918,522 11.91 5.0 74.6 52.0 50.3 39.5 Non-Muslims, Non-IPs 11,287,301 70.06 7.8 93.4 67.7 80.9 56.8 All groups 16,111,584 100 7.1 87.7 61.5 73.9 51.3 2010 Muslims 4,716,222 21.98 6.0 84.7 51.5 73.8 47.0 Indigenous persons 3,201,321 14.92 5.8 88.9 57.9 62.3 60.2 Non-Muslims, Non-IPs 13,537,939 63.10 8.6 98.4 77.0 91.6 79.9 All groups 21,455,482 100 7.7 94.2 68.5 82.5 70.7 O. S. McDoom et al. 1 3 Table 2 (continued) Group size Group size (%) Schooling Literacy (%) Safe water (%) Sanitation (%) Electricity (%) (years) Visayas 2000 Muslims 22,492 0.16 7.1 88.2 65.3 66.5 41.6 Indigenous persons 1,276,833 9.11 7.7 92.8 65.4 80.4 60.5 Non-Muslims, Non-IPs 12,710,776 90.73 7.3 92.2 66.6 69.6 58.4 All groups 14,010,101 100.00 7.3 92.2 66.5 70.6 58.5 2010 Muslims 39,939 0.22 7.3 91.4 82.3 83.4 80.6 Indigenous persons 1,177,605 6.60 8.2 96.6 68.3 87.7 80.6 Non-Muslims, Non-IPs 16,616,994 93.17 8.1 97.6 73.3 80.6 80.0 All groups 17,834,538 100 8.1 97.6 73.0 81.0 80.0 Luzon 2000 Muslims 107,975 0.28 8.0 90.4 74.6 77.8 74.4 Indigenous persons 2,446,302 6.27 7.4 88.2 68.5 77.2 58.3 Non-Muslims, Non-IPs 36,492,193 93.46 8.8 95.5 82.0 89.6 82.7 All groups 39,046,470 100.00 8.7 95.1 81.1 88.8 81.1 2010 Muslims 241,916 0.47 9.0 96.8 84.8 87.3 82.7 Indigenous persons 3,412,050 6.60 8.2 94.8 68.3 83.8 73.2 Non-Muslims, Non-IPs 48,018,407 92.93 9.5 99.2 85.9 94.4 91.2 All groups 51,672,373 100 9.4 98.9 84.7 93.6 90.0 Statistics based on individuals for whom data on education, literacy, safe water, sanitation, electricity, ethnicity, religion were all collected. This excluded from the analysis approximately 9% of the sample in 2000 and 1% in 2010 Inequality Between Whom? Patterns, Trends, and Implications… a decline using Gini). It has also found that while urban inequality has declined, rural ine- quality has increased (Kanbur and Zhuang 2013). Research has also examined spatial inequality along subnational administrative bound- aries, typically regions and provinces, and pointed to the growing disparity between the National Capital Region in Luzon and the rest of the country; or else between regions connected to the global economy, for instance coastal areas of Visayas with strong tourist industries or regions with Special Economic Zones on the one hand and rural hinterland or otherwise peripheral regions on the other (Clausen 2010). Globalization features promi- nently as an explanatory factor in this research (Akita and Pagulayan 2014; Clausen 2010) and one study has pointed specifically to international migration and the role of remit- tances from the large number of Filipinos working overseas in increasing income inequal- ity (Edgard R. Rodriguez 1998). Individuals with the skills and training that enable them to take up employment opportunities abroad typically come from already highly-developed regions. Decentralization, often promoted as supportive of policies aimed at inequality reduction, has been found to have either, at best, no or an ambiguous effect on inequality in the Philippines (Akita and Pagulayan 2014; Hill 2008) or, at worst, a role in entrenching the power of local, often autocratic elites uninterested in redistribution (Sidel 2014). In contrast, research on between-group inequality in the Philippines has been lim- ited. McDoom and Gisselquist (2016) documented patterns and trends in between-group inequality in Mindanao and also its role in inhibiting social integration there (McDoom 2018). However, there has been no research examining horizontal inequality’s relationship with the many other adverse phenomena that research in other contexts has documented. Arguably the strongest consensus has formed in respect of its association with violent con- flict (Østby 2008; Mancini 2005; Stewart 2010; Gubler and Selway 2012; Cederman et al. 2011; Murshed and Gates 2005) where the disparity between ethnic groups is believed to be a source of grievance that motivates rebellion against the state or violence between groups. Grievance also features strongly in descriptive accounts of the conflicts that have beset the Philippines, in particular the insurgencies waged by Moro rebel groups in Mind- anao (McKenna 1998; Lara 2014; Gutierrez et al. 2000; Majul 1988). Accounts emphasize Moro resentment in several respects: their numerical minorization by settlers from Luzon and Visayas; their dispossession from lands they had historically controlled; their inferior socio-economic status vis-à-vis non-Muslim and non-indigenous communities; and the relatively limited resources allocated to areas they inhabit by the central government in Manila. This sentiment is exacerbated by the historical context in which the Moro had once been the politically and socially ascendant grouping in Mindanao. One implication of high and increasing between-group inequality to consider in the Philippines context then is its potential association with social and political stability. 4 Data and Methods We draw on 10 and 20% samples of the 2000 and 2010 Philippines Population and Housing Censuses respectively that provided individual-level data on roughly 7 and 20 million individuals. We examined 5 non-income indicators of inequality: (1) average years of schooling (among those aged 25 and over); (2) literacy status (among those aged 10 and over); (3) access to safe drinking water; (4) access to sanitary toilet facili- ties; (5) and access to electricity. We included only individuals for whom data on all 5 indicators and ethnicity were available. Our criterion excluded only 1% of the 2010 sample but 9% of the 2000 sample, suggesting higher data quality collection in 2010. 1 3 O. S. McDoom et al. Importantly, ethnicity data were well-reported with only 1.1% missing in 2000 and 0.5% in 2010. Using these 5 indicators, we then measure total, within-group, and between- group inequality at the national and then at each of the three regional levels. Specifi- cally, we calculate the Gini coefficient and Theil index for total and within-group ine- quality at national and subnational levels, and then the GGini, GTheil, and Grouped Coefficient of Variation (GCOV) for between-group inequality, again at the national and subnational levels. Each of the between-group inequality measures is calculated as follows. R S GGini = p p y ̄ − y ̄ , r s r s 2y ̄ r s 1 n where y ̄ = y is group r’s mean value; R is group r’s population size; p is group r’s r ir r population share; y is the quantity of the variable of interest (e.g., years of education) of ir the ith member of group r. y ̄ y ̄ r r GTheil = p log , y ̄ y ̄ where y ̄ = y is group r’s mean value; R is group r’s population size; p is group r’s r ir r population share; y is the quantity of the variable of interest (e.g., years of education) of ir the ith member of group r. R 2 GCOV = p y ̄ − y ̄ , r r y ̄ 1 n where y ̄ = y is group r’s mean value; R is the number of groups; p is group r’s r ir r population share; y is the quantity of the variable of interest (e.g., years of education) of ir the ith member of group r. We also examine the relationship between horizontal inequality and social and politi- cal instability in the Philippines. Horizontal inequality is measured for 2010 using a Gini coefficient calculated using all 5 non-income indicators described above that have been aggregated into an index using principal components analysis. Social and political instabil- ity is measured using data from the Philippines Office of Civil Defense that recorded inci- dents of organized armed attacks, individual grenade or bomb explosions, and displace- ments of individuals due to conflict throughout the country. We examined incidents that occurred between 2010 and 2013 to help disentangle the potentially endogenous relation- ship between horizontal inequality and political and social instability. The model specified controls for population size, land area, poverty levels, road density (indicative of the rela- tive mobility of state and rebel forces), and the extent of school infrastructure (indicative of developmental levels). We also include location dummies for the three major island groups with Mindanao as the reference group. The exact definitions of the co-variates are provided in Table 3 along with their sources. We utilized Poisson regression given the count nature of the dependent variable and measured all variables at the municipality level. In 2010, the Philippines territorial hierarchy comprised 17 regions, 85 provinces, 1491 municipalities, and 42,025 barangays. 1 3 Inequality Between Whom? Patterns, Trends, and Implications… 1 3 Table 3 Variable definitions Variable Description Source Social and political instability Number of incidents of organized armed attacks, bomb/grenade Philippines Office of Civil Defense explosions, and conflict-induced displacement in municipality between 2010 and 13 Horizontal inequality Gini coefficient for between-group inequality indexed for schooling, Philippines Population and Housing Census 2010 literacy, safe water, sanitation, and electricity in 2010 Population size Number of residents in municipality in 2010 (in 1000s) Philippines Population and Housing Census 2010 Land area Area of municipality in sq.km Philippines Land Management Bureau Poverty Percentage of families/individuals with per capita income/expendi- Philippines Statistics Authority poverty incidence estimates ture less than the per capita poverty threshold Road density Ratio of road network length to land area (km of road per 100 sq. km. Philippines Department of Public Works and Highways (road net- of land area) in 2009 work); Philippines Land Management Buruea (land area) School density Ratio of elementary schools to number of barangays in municipality Philippines Department of Education Basic Information Education in 2009 System O. S. McDoom et al. 5 Results 5.1 National‑Level Analysis At the national level the data present a broadly positive portrait of non-income inequal- ity in the Philippines. Total inequality in 2010, expressed as a Gini coefficient, does not exceed 0.24 on any of the 5 dimensions. The highest inequality is in schooling. It is worth noting that, in contrast with the Gini, the Theil index suggests inequality is higher in terms of access to services than in education, reflecting the higher sensitivity of the Gini to changes in the middle of the distribution. Decomposition analysis reveals that the contribution of within-group inequality—that is within the Muslims, indigenous per- sons, and non-Muslim, non-indigenous groupings—to total inequality greatly exceeds that of between-group inequality both in 2000 and 2010. However, caution should be exercised in interpreting the policy significance of this fact given the higher normative premium usually attached to between-group inequality as well as its potentially stronger adverse effects (Kanbur 2006). The trend is also favorable. Total inequality declined on all 5 dimensions between 2000 and 2010 with the strongest decline observed in access to electricity, likely reflecting investments in rural electrification made during the Arroyo administration (2001–10). Table 4 summarizes the findings in respect of total inequality. Within-group inequality at the national level reveals important differences between groupings. Muslims have, by far, the highest within-group inequality on all 5 dimen- sions. It is at least twice as high on all dimensions in 2010 compared with non-Muslim, non-indigenous persons who have the lowest within-group inequality levels of all three groupings in 2000 and 2010. Sub-group analysis reveals an important divide within the Muslim grouping: Muslims who are also classified as indigenous persons are much less well-off than Muslims who are not, particularly in respect of education levels. Tellingly, indigenous Muslims are also less well-off than indigenous non-Muslims. Being Muslim and being indigenous then is a double disadvantage. As with total inequality, the trend in within-group inequality is also favourable. It declined between 2000 and 2010 for all three groupings. However, disparities again exist between them. Indigenous persons had the smallest percentage decline on 4 dimensions and non-Muslim, non-indigenous per- sons the largest relative decrease on all 5 dimensions. Table 5 summarizes the findings in respect of within-group inequality. Between-group inequality presents a slightly less positive picture at the national level. Scores are of similar magnitude on almost on all dimensions except literacy where the disparities between groups are less pronounced. This is true for all three measures employed: GTheil, GGini, and GCOV. The between-group inequality scores reflect the much lower socio-economic status, described earlier, that Muslims and indigenous per- sons possess compared with everyone else. Muslims had ranked last for schooling, lit- eracy, and safe water access and indigenous persons for sanitation and electricity access in 2010. In contrast with total and within-group inequality, between-group inequality’s trend is not upward across all 5 dimensions. It in fact worsened in respect of school- ing and safe water when measured by GCOV and GGini. The trend data, however, are not unambiguous as the GTheil suggests these dimensions improved. Literacy showed the strongest relative improvement, reflecting perhaps the attempt to mainstream the national curriculum in private Islamic schools, or madrassahs. Table 6 summarizes the findings in respect of between-group inequality. 1 3 Inequality Between Whom? Patterns, Trends, and Implications… Table 4 Total inequality in the Philippines in 2000 and 2010 Schooling Literacy Safe water Sanitation Electricity access access access 2000 2010 2000 2010 2000 2010 2000 2010 2000 2010 Philippines Theil Within-group 0.135 0.110 0.073 0.024 0.301 0.235 0.198 0.119 0.353 0.175 Between-group 0.004 0.004 0.001 0.001 0.005 0.005 0.004 0.003 0.008 0.005 Total 0.138 0.114 0.074 0.025 0.307 0.241 0.202 0.122 0.361 0.181 Gini Within-group 0.210 0.183 0.045 0.010 0.191 0.144 0.129 0.071 0.221 0.104 Between-group 0.025 0.027 0.016 0.011 0.031 0.034 0.024 0.024 0.040 0.035 Overlap 0.039 0.035 0.011 0.003 0.042 0.036 0.030 0.019 0.043 0.026 Total 0.275 0.244 0.072 0.024 0.264 0.214 0.183 0.114 0.303 0.165 Mindanao Theil Within-group 0.189 0.167 0.125 0.058 0.469 0.364 0.285 0.181 0.646 0.329 Between-group 0.015 0.014 0.005 0.002 0.014 0.014 0.014 0.012 0.014 0.017 Total 0.204 0.181 0.131 0.060 0.483 0.378 0.299 0.192 0.660 0.347 Gini Within-group 0.174 0.146 0.045 0.015 0.192 0.129 0.116 0.056 0.254 0.115 Between-group 0.074 0.076 0.046 0.030 0.074 0.080 0.071 0.073 0.075 0.088 Overlap 0.081 0.085 0.031 0.012 0.117 0.105 0.071 0.045 0.154 0.089 Total 0.329 0.307 0.123 0.057 0.383 0.313 0.259 0.174 0.484 0.292 Visayas Theil Within-group 0.170 0.141 0.081 0.025 0.407 0.315 0.347 0.210 0.535 0.222 Between-group 0.000 0.000 0.000 0.000 0.000 0.000 0.001 0.000 0.000 0.000 Total 0.170 0.141 0.081 0.025 0.407 0.315 0.348 0.210 0.535 0.222 Gini Within-group 0.258 0.247 0.065 0.021 0.277 0.234 0.248 0.169 0.340 0.174 Between-group 0.005 0.001 0.001 0.001 0.002 0.004 0.013 0.005 0.003 0.000 Overlap 0.049 0.035 0.012 0.003 0.056 0.031 0.033 0.016 0.066 0.025 Total 0.312 0.282 0.078 0.024 0.335 0.270 0.294 0.190 0.415 0.200 Luzon Theil Within-group 0.101 0.079 0.050 0.011 0.209 0.164 0.118 0.065 0.206 0.104 Between-group 0.001 0.001 0.000 0.000 0.001 0.001 0.001 0.000 0.003 0.001 Total 0.102 0.080 0.051 0.011 0.209 0.166 0.118 0.066 0.209 0.106 Gini Within-group 0.206 0.177 0.040 0.007 0.160 0.125 0.092 0.050 0.156 0.078 Between-group 0.009 0.008 0.005 0.003 0.010 0.013 0.009 0.007 0.018 0.013 Overlap 0.022 0.020 0.005 0.001 0.019 0.015 0.011 0.007 0.015 0.010 Total 0.237 0.204 0.049 0.011 0.189 0.153 0.112 0.064 0.189 0.100 1 3 O. S. McDoom et al. Table 5 Within-group inequality in the Philippines in 2000 and 2010 Schooling Literacy Safe water Sanitation Electricity access access access 2000 2010 2000 2010 2000 2010 2000 2010 2000 2010 Philippines Gini Muslims 0.479 0.431 0.262 0.147 0.552 0.467 0.482 0.363 0.587 0.385 Indigenous persons 0.356 0.337 0.151 0.072 0.377 0.360 0.250 0.197 0.484 0.365 Non-Muslims, Non-IPs 0.258 0.226 0.056 0.013 0.239 0.183 0.162 0.091 0.272 0.131 Theil Muslims 0.451 0.362 0.304 0.159 0.802 0.628 0.657 0.450 0.883 0.486 Indigenous persons 0.238 0.212 0.163 0.075 0.473 0.446 0.288 0.220 0.661 0.453 Non-Muslims, Non-IPs 0.119 0.095 0.057 0.013 0.273 0.202 0.176 0.095 0.317 0.141 Mindanao Gini Muslims 0.488 0.441 0.270 0.153 0.564 0.485 0.493 0.377 0.599 0.398 Indigenous persons 0.432 0.393 0.254 0.111 0.477 0.421 0.315 0.262 0.629 0.530 Non-Muslims, Non-IPs 0.274 0.249 0.066 0.016 0.321 0.230 0.189 0.084 0.429 0.201 Theil Muslims 0.468 0.377 0.314 0.166 0.830 0.663 0.678 0.472 0.913 0.507 Indigenous persons 0.359 0.287 0.293 0.117 0.648 0.546 0.377 0.304 0.991 0.755 Non-Muslims, Non-IPs 0.131 0.111 0.068 0.016 0.386 0.262 0.209 0.088 0.560 0.224 Visayas Gini Muslims 0.314 0.343 0.118 0.086 0.346 0.177 0.335 0.166 0.584 0.194 Indigenous persons 0.298 0.284 0.072 0.034 0.346 0.317 0.196 0.123 0.395 0.194 Non-Muslims, Non-IPs 0.314 0.282 0.078 0.024 0.334 0.267 0.304 0.194 0.416 0.200 Theil Muslims 0.179 0.233 0.125 0.090 0.425 0.195 0.408 0.182 0.875 0.216 Indigenous persons 0.157 0.149 0.074 0.034 0.424 0.380 0.218 0.131 0.503 0.216 Non-Muslims, Non-IPs 0.171 0.141 0.082 0.024 0.405 0.311 0.362 0.216 0.538 0.223 Luzon Gini Muslims 0.291 0.235 0.096 0.032 0.254 0.152 0.222 0.127 0.256 0.173 Indigenous persons 0.321 0.294 0.118 0.052 0.315 0.317 0.228 0.162 0.417 0.268 Non-Muslims, Non-IPs 0.231 0.198 0.045 0.008 0.180 0.141 0.104 0.056 0.173 0.088 Theil Muslims 0.170 0.117 0.100 0.033 0.293 0.165 0.251 0.136 0.295 0.189 Indigenous persons 0.195 0.166 0.125 0.053 0.378 0.381 0.259 0.177 0.539 0.312 Non-Muslims, Non-IPs 0.096 0.074 0.046 0.008 0.199 0.152 0.109 0.058 0.190 0.092 5.2 Subnational Analysis The portrait of inequality in the Philippines becomes more troubling when the data are disaggregated. In terms of total inequality, important differences between the three island 1 3 Inequality Between Whom? Patterns, Trends, and Implications… Table 6 Between-group inequality in the Philippines in 2000 and 2010 Schooling Literacy Safe water access Sanitation Electricity access access 2000 2010 2000 2010 2000 2010 2000 2010 2000 2010 Philippines GGini 0.0250 0.0270 0.0160 0.0110 0.0310 0.0340 0.0240 0.0240 0.0400 0.0350 GTheil 0.0036 0.0039 0.0014 0.0006 0.0055 0.0054 0.0040 0.0031 0.0082 0.0055 GCOV 0.0852 0.0989 0.0514 0.0386 0.0967 0.1089 0.0841 0.0837 0.1216 0.1062 Mindanao GGini 0.0740 0.0760 0.0460 0.0300 0.0740 0.0800 0.0710 0.0730 0.0750 0.0880 GTheil 0.0146 0.0142 0.0054 0.0020 0.0136 0.0140 0.0135 0.0117 0.0139 0.0173 GCOV 0.1691 0.1781 0.1020 0.0682 0.1597 0.1781 0.1590 0.1618 0.1647 0.1840 Visayas GGini 0.0050 0.0010 0.0010 0.0010 0.0020 0.0040 0.0130 0.0050 0.0030 0.0000 GTheil 0.0001 0.00001 0.0000 0.00001 0.00001 0.0002 0.0009 0.0002 0.0001 0.0000 GCOV 0.0163 0.0053 0.0026 0.0041 0.0061 0.0179 0.0441 0.0217 0.0152 0.0018 Luzon GGini 0.0090 0.0080 0.0050 0.0030 0.0100 0.0130 0.0090 0.0070 0.0180 0.0130 GTheil 0.0008 0.0006 0.0002 0.0001 0.00087 0.0014 0.0006 0.0004 0.0029 0.0013 GCOV 0.0395 0.0353 0.0188 0.0112 0.0368 0.0506 0.0334 0.0284 0.0760 0.0498 groups become apparent. Mindanao has, by far, the highest level of total inequality on all 5 non-income dimensions. In 2010, the Gini coefficient for Mindanao was 0.307 for school- ing, for instance, but only 0.204 for Luzon. Luzon had the lowest levels of total inequality on all dimensions. The picture darkens further when one remembers the descriptive statis- tics confirm Mindanao is already the most under-developed and Luzon the most-developed of the three island groups. Although the trend is upward in all three regions, Mindanao lags behind, registering the smallest improvement in the Gini coefficient on all 5 dimensions between 2000 and 2010. The gap in total inequality between Mindanao and the rest of the country then widened in the intervening decade. Within-group inequality patterns at the subnational level also challenge the narrative suggested by the national-level data. To begin with, contrary to their overall situation at the national-level, Muslims do not have the highest within-group inequality across all three island groups. Only in Mindanao is within-group inequality higher for Muslims than the other two groups. In Luzon and Visayas, Muslims in fact rank second in terms of within- group inequality. To take education as an example, the Theil index indicated inequality among Muslims in Mindanao was 0.377 in 2010 but only 0.232 and 0.170 in Visayas and Luzon respectively. This is consistent with the descriptive statistics. Muslims in Luzon are much better-off than Muslims in Mindanao. Taking education again, Muslims in Luzon had an average of 9 years of schooling compared with only 6 years for Muslims in Mindanao. Consistent with the national level analysis, however, the trend in within-group inequality is upwards for Muslims across all three island groups between 2000 and 2010 on almost every dimension. Perceptions of the position of indigenous persons also change when within-group is examined at the subnational level. While they have the highest within-group inequality in Luzon and rank second in Mindanao, they have the lowest within-group inequality of 1 3 O. S. McDoom et al. all three groupings in Visayas. The descriptive statistics shed further light on differences between island groups in the position of indigenous persons. While they have the lowest scores in Luzon on 5 dimensions, they have the highest scores on 4 dimensions in Visayas. However, this is relative to the other two groups. In absolute terms, the situation of indig- enous persons is broadly similar in Luzon and Visayas. It is only in Mindanao that a dis- crepancy becomes apparent where indigenous persons are much worse off than indigenous communities in the other two island groups. Taking education again, the average indig- enous person in Mindanao had received 5.8 years of schooling compared with 8.2 years in both Luzon and Visayas. As with Muslims, the trend in inequality among indigenous person was also positive between 2000 and 2010 across all three island groups, again con- sistent with the overall national-level trend. It is in respect of between-group inequality that the risks of reliance on national-level measures become most apparent. An important difference exists between the three island groups with Mindanao again the outlier. Between-group inequality was several times higher in Mindanao than in Luzon and Visayas on all dimensions in 2010. Between-group inequality was roughly 0.17 in Mindanao on all dimensions, except literacy which was lower, when measured by GCOV. In contrast, in Luzon and Visayas between-group ine- quality values were an order of magnitude smaller on these same dimensions. For instance, between-group inequality in education in Mindanao was 0.1781 in 2010 but only 0.0053 and 0.0353 in Visayas and Luzon respectively. These differences are not solely explained by differences in the size of the three ethno-religious blocs in each island group. Non- Muslim, non-indigenous persons represented between 87, 91, and 93% of the population in Mindanao, Visayas, and Luzon respectively. The largest driver remains the disparity in the situation of Muslims and indigenous persons on the one hand and everyone else on the other. This disparity is much greater in Mindanao than in the other two island groups as the descriptive statistics corroborate. Furthermore, the picture worsens when we examine the trend data. Consistent with the national-level trend, between-group inequality improved in Luzon and Visayas between 2000 and 2010 on most of the dimensions. However, contrary to this trend, Mindanao’s between-group inequality scores worsened on all dimensions except literacy in the intervening decade. Not only is between-group inequality higher in Mindanao than anywhere else, the disparities between the three ethno-religious blocs have also gotten worse. 5.3 Between‑Group Inequality and Socio‑political Instability Consistent with the theorized prediction we find a substantively and statistically significant association between horizontal inequality and socio-political instability at the subnational level. The relationship is positive. As disparities between the three ethno-religious groups increase, instability also increases. More precisely, the interpretation of the incidence rate ratios we report in Table 7 is as follows: a one unit increase in between-group inequality increases the rate of instability incidents by 9.7%, holding all other variables constant. It is important to note that the location dummies highlight the distinctive situation of Mind- anao. Not being in Luzon or Visayas i.e. being present in Mindanao increases the incident rate by over 900%. Overwhelmingly, socio-political instability is concentrated in Mindanao which also has, by far, the highest level of between-group inequality of the three regions. Evidently, horizontal inequality is not the only potential driver of instability. We also find statistically significant positive associations with population size, land area, and poverty. As these increase, so too does instability. In contrast, road and school density decrease the 1 3 Inequality Between Whom? Patterns, Trends, and Implications… Table 7 Predictors of socio- Variable Incidence rate ratio Standard error political instability at subnational level in the Philippines Horizontal inequality 1.0971*** 0.0245 Population size 1.0008* 0.0004 Land area 0.9993** 0.0003 Poverty 1.0000*** 0.0000 Road density 0.9935** 0.0023 School density 0.4754* 0.1417 Luzon dummy 0.0997*** 0.0276 Visayas dummy 0.1050*** 0.0348 Constant 0.7254 0.2426 N 1620 Pseudo-R 0.34 Results estimated using Poisson regression; statistical significance *p < 0.05; **p < 0.01; ***p < 0.001 rate of instability incidents. Their interpretation is not unequivocal. On the one hand, they may indicate a municipality’s level of infrastructural development. More highly-developed municipalities are less likely to experience instability. On the other hand, road density may also indicate the feasibility of insurgent attacks. In municipalities where roads are exten- sive, it is relatively easy for the state to project its coercive power as it facilitates the mobil- ity of police and military forces. Such municipalities are also likely to be unsuitable for guerrilla tactics. 6 Conclusion Our findings underscore the importance of localized analysis of inequality and in particular the challenge facing researchers of choosing the appropriate spatial and social boundaries along which inequality should be examined. The choice is crucial if the objective is to help policy-makers decide what type of intervention, if any, is required to mitigate inequality’s potentially adverse consequences. We selected geographic areas and social groups based on our judgement of their socio-political significance in the Philippines context. In making this judgement we considered how resilient to the passage of time these boundaries had been, indicated for example by the persistence of conflict and violence along them, and also the extent to which they had been formally institutionalized. To our knowledge, this is the first time between-group inequality has been analysed in the Philippines using these particular social groupings. Our work highlights the distinctiveness of Mindanao, as one of the three geographic areas examined, and the subordinate position of Muslims and indig- enous persons in particular, as two of the three social groups considered. However, it also finds that the situation of Muslims and indigenous persons varies with region. It is not as problematic in Luzon and Visayas as it is in Mindanao. Our choice of spatial and social boundaries is evidently not beyond criticism. We are keenly aware there exists, for instance, considerable sub-group diversity among Muslims, indigenous peoples, and the residual ‘everyone else’ category that we have not examined. Area specialists may argue there exist within these three major groupings social bounda- ries of even greater socio-political significance that we have ignored. Similarly, within the 1 3 O. S. McDoom et al. three major island groups, important differences exist. The position of the National Capi- tal Region compared with the Cordillera Administrative Region in Luzon and the Davao Region against the Autonomous Region of Muslim Mindanao in Mindanao make stark contrasts for example. It remains open for others to conduct research on inequality along boundaries they adjudge more salient. The article also explored one implication of one of the subnational disparities identified. We focused on between-group inequality. The association we identified between horizontal inequality and socio-political instability is consistent with the mounting evidence linking it with civil conflict in a growing number of country contexts. We emphasize, however, that the approach we used does not permit causal inference. We readily acknowledge the pos- sibility of other unobserved conflict drivers as well as the strong likelihood of a feedback loop between violence and inequality. Not only may between-group inequality motivate conflict, it may also be shaped by it. In the Philippines context, conflict-induced displace- ment may well be driving the socio-economic scores of Muslims and indigenous persons. Many such individuals have been concentrated in areas in which conflict is present and have been forced to migrate to areas where their status has become more marginal. Finally, having documented the existence of worrisome patterns and trends in within- group and between-group inequality at the subnational level in the Philippines, we believe a priority for future research will be to identify the drivers behind them with a view to helping social planners formulate appropriate redistributive policies. The literature sug- gests many possibilities but we highlight one debate whose resolution we believe particu- larly important. To what extent is this inequality the result of decisions and actions taken at the national level and to what extent is it the product of more local forces? In the Philip- pines context, both seem plausible. The arena for national-level politics is Luzon wherein a dynastic elite class operates primarily to protect their private interests. Mindanao and to a lesser extent Visayas are peripheral regions and have been historically under-represented in national-level politics. At the same time, patronage politics are prevalent at the local level and local political elites have a strong interest in preserving the asymmetric nature of social relations in their communities. The answer to this question is not inconsequential. Decentralization is commonly presented as one way to address center-periphery inequali- ties and a significant level of resources are consequently allocated to its promotion and implementation. Acknowledgements The authors thank Maria Blesila D. Mondez and Arkin A. Arboneda for their research assistance; the Philippines National Commission on Indigenous People (NCIP) for their advice on ethnic classifications; and the Philippines Statistics Authority for providing the census data. All errors in the paper naturally are our own. Funding was provided by UNU-WIDER. 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