arXiv subjects

Anand Sahasranaman

Publications and source records attributed to Anand Sahasranaman.

16 recordsLinked to original sources

arXiv2024

Urbanization, economic development, and income distribution dynamics in India

India's urbanization is often characterized as particularly challenging and very unequal but systematic empirical analyses, comparable to other nations, have largely been lacking. Here, we characterize India's economic and human development along with changes in its personal income distribution as a function of the nation's growing urbanization. On aggregate, we find that India outperforms most other nations in the growth of various indicators of development with urbanization, including income and human development. These results are due in part to India's present low levels of urbanization but also demonstrate the transformational role of its cities in driving multi-dimensional development. To test these changes at the more local level, we study the income distributions of large Indian cities to find evidence for high positive growth in the lowest decile (poorest) of the population, enabling sharp reductions in poverty over time. We also test the hypothesis that inequality-reducing cities are more attractive destinations for rural migrants. Finally, we use income distributions to characterize changes in poverty rates directly. This shows much lower levels of poverty in urban India and especially in its largest cities. The dynamics of poverty rates during the recent COVID-19 pandemic shows both a high fragility of these improvements during a crisis and their resilience over longer times. Sustaining a long-term dynamic where urbanization continues to be closely associated with human development and poverty reduction is likely India's fastest path to a more prosperous and equitable future.

physics.soc-ph↗

arXiv2020

Distribution of neighborhood size in cities

We study the distribution of neighborhoods across a set of 12 global cities and find that the distribution of neighborhood sizes follows exponential decay across all cities under consideration. We are able to analytically show that this exponential distribution of neighbourhood sizes is consistent with the observed Zipf's Law for city sizes. We attempt to explain the emergence of exponential decay in neighbourhood size using a model of neighborhood dynamics where migration into and movement within the city are mediated by wealth. We find that, as observed empirically, the model generates exponential decay in neighborhood size distributions for a range of parameter specifications. The use of a comparative wealth-based metric to assess the relative attractiveness of a neighborhood combined with a stringent affordability threshold in mediating movement within the city are found to be necessary conditions for the the emergence of the exponential distribution. While an analytical treatment is difficult due to the globally coupled dynamics, we use a simple two-neighbourhood system to illustrate the precise dynamics yielding equilibrium non-equal neighborhood size distributions.

physics.soc-ph↗

arXiv2020

Long term dynamics of poverty transitions in India

We model the dynamics of poverty using a stochastic model of Geometric Brownian Motion with reallocation (RGBM) and explore both transient and persistent poverty over 1952-2006. We find that annual transitions in and out of poverty are common and show a rising trend, with the rise largely being driven by transitions out of poverty. Despite this promising trend, even toward the end of the time frame, there is a non-trivial proportion of individuals still transitioning annually into poverty, indicative of the economic fragility of those near the poverty line. We also find that there is still a marked persistence of poverty over time, though the probability of poverty persistence is slowly declining. Particularly concerning in this context are the poverty trajectories of those at the very bottom of the income distribution. The choice of poverty line appears to impact the dynamics, with higher poverty lines corresponding to lower transitions and higher persistence probabilities. The distinct nature of emergent transient and persistence dynamics suggests that the approaches to counter these phenomena need to be different, possibly incorporating both missing financial markets and state action.

q-fin.GN↗

arXiv2020

Spread of Covid-19 in urban neighbourhoods and slums of the developing world

We study the spread of Covid-19 across neighbourhoods of cities in the developing world and find that small numbers of neighbourhoods account for a majority of cases (k-index~0.7). We also find that the countrywide distribution of cases across states/provinces in these nations also displays similar inequality, indicating self-similarity across scales. Neighbourhoods with slums are found to contain the highest density of cases across all cities under consideration, revealing that slums constitute the most at-risk urban locations in this epidemic. We present a stochastic network model to study the spread of a respiratory epidemic through physically proximate and accidental daily human contacts in a city, and simulate outcomes for a city with two kinds of neighbourhoods - slum and non-slum. The model reproduces observed empirical outcomes for a broad set of parameter values - reflecting the potential validity of these findings for epidemic spread in general, especially across cities of the developing world. We also find that distribution of cases becomes less unequal as the epidemic runs its course, and that both peak and cumulative caseloads are worse for slum neighbourhoods than non-slums at the end of an epidemic. Large slums in the developing world therefore contain the most vulnerable populations in an outbreak, and the continuing growth of metropolises in Asia and Africa presents significant challenges for future respiratory outbreaks from perspectives of public health and socioeconomic equity.

physics.soc-ph↗

arXiv2020

Poverty in the time of epidemic: A modelling perspective

We create a network model to study the spread of an epidemic through physically proximate and accidental daily human contacts in a city, and simulate outcomes for two kinds of agents - poor and non-poor. Under non-intervention, peak caseload is maximised, but no differences are observed in infection rates across poor and non-poor. Introducing interventions to control spread, peak caseloads are reduced, but both cumulative infection rates and current infection rates are systematically higher for the poor than for non-poor, across all scenarios. Larger populations, higher fractions of poor, and longer durations of intervention are found to progressively worsen outcomes for the poor; and these are of particular concern for economically vulnerable populations in cities of the developing world. Addressing these challenges requires a deeper, more rigorous understanding of the relationships between structural poverty and epidemy, as well as effective utilization of extant community level infrastructure for primary care in developing cities. Finally, improving iniquitous outcomes for the poor creates better outcomes for the whole population, including the non-poor.

physics.soc-ph↗

arXiv2020

Dynamics of reallocation within India's income distribution

We investigate the nature and extent of reallocation occurring within the Indian income distribution, with a particular focus on the dynamics of the bottom of the distribution. Specifically, we use a stochastic model of Geometric Brownian Motion with a reallocation parameter that was constructed to capture the quantum and direction of composite redistribution implied in the income distribution. It is well known that inequality has been rising in India in the recent past, but the assumption has been that while the rich benefit more than proportionally from economic growth, the poor are also better off than before. Findings from our model refute this, as we find that since the early 2000s reallocation has consistently been negative, and that the Indian income distribution has entered a regime of perverse redistribution of resources from the poor to the rich. Outcomes from the model indicate not only that income shares of the bottom decile (~1%) and bottom percentile (~0.03%) are at historic lows, but also that real incomes of the bottom decile (-2.5%) and percentile (-6%) have declined in the 2000s. We validate these findings using income distribution data and find support for our contention of persistent negative reallocation in the 2000s. We characterize these findings in the context of increasing informalization of the workforce in the formal manufacturing and service sectors, as well as the growing economic insecurity of the agricultural workforce in India. Significant structural changes will be required to address this phenomenon.

econ.EM↗

arXiv2020

Income distribution and inequality in India: 2014-19

We study the evolution of income in India from 2014-19 and find that while income inequality remains largely consistent over this time, the lower end of the income distribution has experienced significant losses - the bottom ventile shows not only a decline in income share of ~38%, but also negative real average income growth of -4.6% per annum. We further investigate the composition of this part of the distribution using rural and urban splits, and find that even as income shares at the bottom of the urban distribution have increased over time, those at the bottom of the rural distribution have decreased - income share of bottom decile of the rural income distribution declined by ~41%, and real average income growth was at -4.3% per annum from 2014-19. We also empirically confirm that the bottom ventile of the consolidated Indian income distribution is composed primarily of rural incomes, and therefore the decline in real incomes is essentially a rural phenomenon. Studying occupation data of households, we find that the bottom decile of the rural distribution correlates strongly with occupations of small/marginal farmers and agricultural labour, highlighting the increasing economic fragility of such occupations. Using the RGBM model to estimate the nature of reallocation in the Indian income distribution, we find that reallocation has been decreasing from 2015 and even turned negative in 2018, which is in keeping with empirical evidence of real income declines at the bottom of the distribution, and heralds the risk that persistent negative reallocation in the future could result in regressive redistribution of resources from the poor to the rich.

physics.soc-ph↗

arXiv2020

Economic complexity and capabilities of Indian States

We explore economic competitiveness of Indian states based on the economic complexity algorithm, using a pair of coupled non-linear maps to characterize the Fitness of states and Complexity of products exported by them. We find that states produce almost all products within their productive capabilities - diversifying rather than specializing, and that the probability of coexistence of any pair of productive capabilities is maximized when capabilities are of similar complexity. Therefore, states require long time horizons to build complex capabilities and diverse products. We contextualize Fitness using human development, and find an emergent typology of states. Of most concern are the states of Odisha, Uttar Pradesh, and Bihar, stuck in vicious feedback cycles of poor economic complexity and low human development. Economic complexity also reveals significant concerns with the economic trajectories of Punjab, Gujarat, and West Bengal. We discuss these emergent trends within the framework of India's modern economic history.

physics.soc-ph↗

arXiv2020

Network structure of COVID-19 spread and the lacuna in India's testing strategy

We characterize the network of COVID-19 spread in India and find that the transmission rate is 0.43, with daily case growth driven by individuals who contracted the virus abroad. We explore the question of whether this represents exponentially decaying dynamics or is simply an artefact of India's testing strategy. Testing has largely been limited to individuals travelling from high-risk countries and their immediate contacts, meaning that the network reflects positive identifications from a biased testing sample. Given generally low levels of testing and an almost complete absence of testing for community spread, there is significant risk that we may be missing out on the actual nature of outbreak. India still has an apparently low current caseload, with possibly a small window of time to act, and should therefore aggressively and systematically expand random testing for community spread, including for asymptomatic cases. This will help understand true transmission characteristics and plan appropriately for the immediate future.

q-bio.PE↗

arXiv2019

Life Between the City and the Village: Comparative Analysis of Service Access in Indian Urban Slums

The emergence of India as an urbanized nation is one of the most significant socioeconomic and political processes of the 21st century. An essential feature of India's urbanization has been the growth and persistence of informal settlements (slums) in its fast-developing cities. Whether living conditions in Indian urban slums constitute a path to human development or a poverty trap is therefore an issue of vital importance. Here, we characterize census data using the framework of urban scaling to systematically characterize the relative properties of Indian urban slums, focusing on attributes of neighborhoods such as access to basic services like water, sanitation, and electrical power. We find that slums in larger cities offer systematically higher levels of service access than those in smaller cities. Perhaps as expected, we also find consistent underperformance in service access in slums in comparison with non-slum neighborhoods in the same cities. However, urban slums, on average, offer greater access to services than neighborhoods in rural areas. This situation, which we quantify systematically, may help explain why Indian larger cities have remained attractive to rural populations in terms of living standards, beyond the need for an economic income premium.

physics.soc-ph↗

arXiv2019

A self-consistent assessment of multi-dimensional fitness of cities

Given the importance of urban sustainability and resilience to the future of our planet, there is a need to better understand the interconnectedness between the social, economic, environmental, and governance outcomes that underline these frameworks. Here, we propose a synthesis of the independent scientific frameworks of economic complexity and urban scaling into a consistent mechanism - termed 'city complexity' - to measure the fitness of cities across multiple dimensions. Essentially, we propose the use of urban scaling as the basis to construct and populate a bipartite city-outcome matrix, whose entries are the deviations from scaling law for a given set of urban outcomes. This matrix forms the input into the economic complexity methodology, which iterates over a pair of coupled non-linear maps, computing fitness of cities and complexity of outcomes. We test our algorithm with data from American cities and find that the emergent city fitness measure is consistent with desired behavior across the set of outcomes studied. We also find temporal evolution of city fitness and outcome complexity to be in agreement with theoretical expectation. Overall, these findings suggest that the city complexity mechanism proposed here produces a robust measure of fitness and can be applied for any set of diverse outcomes, irrespective of the specifics of national urban contexts.

physics.soc-ph↗

arXiv2019

Economic geography and the scaling of urban and regional income in India

We undertake an exploration of the economic income (Gross Domestic Product, GDP) of Indian districts and cities based on scaling analyses of the dependence of these quantities on associated population size. Scaling analysis provides a straightforward method for the identification of network effects in socioeconomic organization, which are the tell-tale of cities and urbanization. For districts, a sub-state regional administrative division in India, we find almost linear scaling of GDP with population, a result quite different from urban functional units in other national contexts. Using deviations from scaling, we explore the behavior of these regional units to find strong distinct geographic patterns of economic behavior. We characterize these patterns in detail and connect them to the literature on regional economic development for a diverse subcontinental nation such as India. Given the paucity of economic data for Urban Agglomerations in India, we use a set of assumptions to create a new dataset of GDP based on districts, for large cities. This reveals superlinear scaling of income with city size, as expected from theory, while displaying similar underlying patterns of economic geography observed for district economic performance. This analysis of the economic performance of Indian cities is severely limited by the absence of higher-fidelity, direct city level economic data. We discuss the need for standardized and consistent estimates of the size and change in urban economies in India, and point to a number of proxies that can be explored to develop such indicators.

physics.soc-ph↗

arXiv2018

Urban Geography and Scaling of Contemporary Indian Cities

This paper attempts to create a first comprehensive analysis of the integrated characteristics of contemporary Indian cities, using scaling and geographic analysis over a set of diverse indicators. We use data at the level of Urban Agglomerations in India from the Census 2011 and from a few other sources to characterize patterns of urban population density, infrastructure, urban services, economic performance, crime and innovation. Many of the results are in line with expectations from urban theory and with the behaviour of analogous quantities in other urban systems in both high and middle-income nations. India is a continental scale, fast developing urban system, and consequently there are also a number of interesting exceptions and surprises related to both specific quantities and strong regional patterns of variation. We characterize these patterns in detail for crime and innovation and connect them to the existing literature on their determinants in a specifically Indian context. The paucity of data at the urban level and the absence of official definitions for functional cities in India create a number of limitations and caveats to any present analysis. We discuss these shortcomings and spell out the challenge for a systematic statistical data collection relevant to cities and urban development in India.

physics.soc-ph↗

arXiv2017

Wealth and Identity: The dynamics of dual segregation

We extend our model of wealth segregation to incorporate migration and study the tendencies towards dual segregation - segregation due to identity (migrants vs. residents) and segregation due to wealth. We find a sharp, non-linear transformation between segregated and mixed-wealth states as neighborhood wealth thresholds become less stringent, allowing agents to move into neighborhoods they cannot afford. The number of such moves required for the onset of this transformation varies inversely with the likelihood of agents willing to move into less wealthy neighborhoods. We also find that this sharp transformation from segregated to mixed wealth states is simultaneously accompanied by a corresponding non-linear transformation from a less identity-segregated to a highly identity-segregated state. We argue that the decrease in wealth segregation does not merely accompany, but in fact drives the increase in identity-based segregation. This implies that lowering wealth segregation necessarily exacerbates identity segregation and that therefore, this trade-off could to be an important consideration in designing urban policy. Additionally, we find that the time taken for the tolerance levels of residents to be breached is significantly lesser under rapid migration. This rapidity of breach of tolerance could potentially underpin the intensity of resident responses to sharp bursts of migration.

physics.soc-ph↗

arXiv2017

Dynamics of Transformation from Segregation to Mixed Wealth Cities

We model the dynamics of the Schelling model for agents described simply by a continuously distributed variable - wealth. Agents move to neighborhoods where their wealth is not lesser than that of some proportion of their neighbors, the threshold level. As in the case of the classic Schelling model where segregation obtains between two races, we find here that wealth-based segregation occurs and persists. However, introducing uncertainty into the decision to move - that is, with some probability, if agents are allowed to move even though the threshold level condition is contravened - we find that even for small proportions of such disallowed moves, the dynamics no longer yield segregation but instead sharply transition into a persistent mixed wealth distribution. We investigate the nature of this sharp transformation between segregated and mixed states, and find that it is because of a non-linear relationship between allowed moves and disallowed moves. For small increases in disallowed moves, there is a rapid corresponding increase in allowed moves, but this tapers off as the fraction of disallowed moves increase further and finally settles at a stable value, remaining invariant to any further increase in disallowed moves. It is the overall effect of the dynamics in the initial region (with small numbers of disallowed moves) that shifts the system away from a state of segregation rapidly to a mixed wealth state. The contravention of the tolerance condition could be interpreted as public policy interventions like minimal levels of social housing or housing benefit transfers to poorer households. Our finding therefore suggests that it might require only very limited levels of such public intervention - just sufficient to enable a small fraction of disallowed moves, because the dynamics generated by such moves could spur the transformation from a segregated to mixed equilibrium.

physics.soc-ph↗

arXiv2017

Cooperative Dynamics of Neighborhood Economic Status in Cities

We significantly extend our earlier variant of the Schelling model, incorporating a neighborhood Potential function as well as an agent wealth gain function to study the long term evolution of the economic status of neighborhoods in cities. We find that the long term patterns of neighborhood relative economic status (RES) simulated by this model reasonably replicate the empirically observed patterns from American cities. Specifically, we find that larger fractions of rich and poor neighborhoods tend to, on average, retain status for longer than lower- and upper-middle wealth neighborhoods. The use of a Potential function that measures the relative wealth of neighborhoods as the basis for agent wealth gain and agent movement appears critical to explaining these emergent patterns of neighborhood RES. This also suggests that the empirically observed RES patterns could indeed be universal and that we would expect to see these patterns repeated for cities around the world. Observing RES behavior over even longer periods of time, the model predicts that the fraction of poor neighborhoods retaining status remains almost constant over extended periods of time, while the fraction of middle-wealth and rich neighborhoods retaining status reduces significantly over time, tending to zero.

physics.soc-ph↗