巴德学院利维经济研究所-仿真、债务和个人收入不平等的股票流一致性模型（英）

Working Paper No. 1099 A Stock-Flow Consistent Model of Emulation, Debt, and Personal Income Inequality by Francesco Ruggeri University of Salerno Riccardo Pariboni University of Siena and Giuliano Toshiro Yajima Levy Economics Institute October 2025 The authors would like to thank Steven Fazzari, Ricardo Summa, Lucas Texeira, Ariel Dvoskin and the participants to the 22nd STOREP Conference and 6th Demand Led Workshop for their comments to earlier drafts of this paper. The usual disclaimers apply. Corresponding author: gyajima@levy.org The Levy Economics Institute Working Paper Collection presents research in progress by Levy Institute scholars and conference participants. The purpose of the series is to disseminate ideas to and elicit comments from academics and professionals. Levy Economics Institute of Bard College, founded in 1986, is a nonprofit, nonpartisan, independently funded research organization devoted to public service. Through scholarship and economic research, it generates viable, effective public policy responses to important economic problems that profoundly affect the quality of life in the United States and abroad. Levy Economics Institute P.O. Box 5000 Annandale-on-Hudson, NY 12504-5000 http://www.levyinstitute.org Copyright © Levy Economics Institute 2025 All rights reserved ISSN 1547-366X 1 ABSTRACT Divergent trends in income and consumption inequality—with the first increasing substantially more than the latter—are an established, stylized fact for the US economy in the last decades. The same time period also experienced a steady increase in household debt, plausibly not independent from the patterns in income distribution and consumption as mentioned. In this article, we develop a stock-flow model that tries to replicate some of these dynamics. We emphasize the role played by changing behavioral attitudes toward consumption and demand for household loans by introducing an emulation mechanism that links the desired consumption for households of a given quintile with the realized consumption of the immediately superior quintile. Furthermore, we leverage the available data on income distribution quintile consumption, income, and wealth to estimate those attitudes empirically. The model, albeit simple and essential in nature, shows the Janus-like faces of household debt and emphasizes the predator-prey–like dynamics implied by a debt-led process, in which fresh borrowing increases aggregate demand and output, which feeds the ability to borrow and consume more; at the same time, the stock of accumulated debt “preys” on income due to the contractionary forces of the repayment mechanism. Through a simple and stylized representation of the multiple interactions between income distribution, consumption, and debt, we also formalize and highlight how the benefits of a process of debt-led growth are asymmetrically distributed and reinforce the same detrimental tendencies in income distribution that led to the emergen