Linking National and Regional Income Inequality: Cross-Country Data Harmonization and Analysis

我们的研究重点是国家内部城镇的收入不平等，以及在五个高收入国家中，这种不平等是如何随着时间的推移而变化的。近年来，学术研究强调了收入不平等的加剧，特别是最高1%收入份额的增加，以及相关的社会，经济和政治问题。越来越清楚的是，这些国民收入不平等部分是由国家内部的收入不平等造成的，“超级明星”全球城市（伦敦、巴黎、纽约）和“落后”的前工业城市之间存在差距。这一点在“民粹主义”政治的兴起中显而易见，生活在经济衰退地区的人们感受到了复杂社会和经济问题的简单化解决方案的吸引力。各国政府和国际组织越来越意识到与国家经济不平等相关的问题，这得益于现有的研究提供了来自不同国家的证据。为了帮助各国政府找到在其城镇、城市和地区更均匀地传播繁荣的方法，需要有国际可比性的证据来显示不同国家在地理不平等方面的表现。到目前为止，由于缺乏关于国家不平等的一致和可比数据集，无法将其分解为国家以下地区，因此无法对基本问题进行调查：地方之间和地方内部日益扩大的差距对整体不平等的影响是什么？是不是一些“超级明星”城市是国家级趋势的主要引擎？国家间不平等的不同演变是否源于国家以下一级的趋势？不同地区的当地生活成本如何随着时间和国家的变化而变化？各国国内收入和经济活动的主要地理分界线是什么？我们的研究将考察自20世纪70年代以来五个高收入国家--加拿大、法国、德国、英国和美国--的地理收入不平等趋势。我们汇集了一个国际专家团队，由具有研究地理不平等经验的地理学家和具有衡量国民收入不平等经验的经济学家组成。我们研究的第一个目标是开发一种方法，以一种可以在国家之间进行比较的方式来分析地理收入不平等。我们将解决三个大问题：定义可比较的地理区域，制定一致的收入衡量标准，并根据不同的当地生活成本（如住房成本）调整收入。我们将使用来自国家税收记录、工人收入登记和家庭调查的数据。使用这种方法，我们的第二个目标是评估地理不平等在推动我们五个研究国家的国民收入不平等方面的重要性。第三，我们将分析国家之间和国家内部的共同趋势和差异，并调查这些趋势的原因。我们的最终目标是利用这个项目作为一个全球数据库的基础，提供有关地方之间不平等的信息。我们的愿景是，这将成为研究人员研究地理收入不平等原因的信息点，并让政府了解他们的国家与其他国家的比较情况。

Our study focuses on income inequality in towns and cities within countries and how this has changed over time in five high-income countries. In recent years, academic research has highlighted the rise of income inequality, particularly the increase of top 1% income share, and the associated social, economic and political problems. It is becoming increasingly clear that these national income inequalities are driven in part by income inequalities within countries, with a divide between the 'superstar' global cities (London, Paris, New York) and 'left behind' ex-industrial towns. This is apparent in the rise of 'populist' politics, in which people living in economically declining places are feeling the pull of simplistic solutions to complex social and economic problems. Governments and international organisations have become increasingly aware of the problems associated with national economic inequality, aided by existing research that provides evidence from different countries. To help governments find ways to spread prosperity more evenly across their towns, cities and regions, there is a need for internationally comparable evidence to show how different countries perform in terms of geographic inequalities. The lack of consistent and comparable datasets on national inequality decomposed into sub-national regions has so far prevented the investigation of fundamental questions: What is the influence of growing disparities across and within local areas on overall inequality? Is it that a few 'superstar' cities are the main engines of country-level trends? Does the divergent evolution of national inequality across countries emerge from trends at the sub-national level? How are local costs of living in different areas evolving over time and across countries? What are the main geographic division lines in terms of income and economic activity within countries? Our study will examine trends in geographic income inequality across five high-income countries - Canada, France, Germany, the United Kingdom and the United States - since the 1970s. We have brought together an international expert team of geographers with experience of studying geographic inequality and economists experienced in measuring national income inequality. The first objective of our research is to develop a method for analysing geographic income inequality in a way that can be compared between countries. We will tackle three big problems: defining comparable geographic areas, having consistent measures of income and adjusting incomes for the varied local cost of living (e.g. housing costs). We will use data from national tax records, from registries of workers' earnings and household surveys. Using this method, our second objective is to assess the importance of geographic inequalities in driving national income inequalities across our five study countries. Third, we will analyse the common trends and differences between and within countries, and investigate the causes of these trends. Our final objective is to use this project as the foundation of a global database that provides information about inequalities between places. Our vision is that this will act as a point of information for researchers to study the causes of geographic income inequality, and for governments to understand how their country compares to others.