This issue of the IMF Research Bulletin opens with a letter from the new editor, Rabah Arezki. The Research Summaries are a "Primer on 'Global Liquidity'" (Eugenio Cerutti, Stijn Claessens, and Lev Ratnovski); and "Trade Integration adn Business Cycle Synchronization" (Kevin Cheng, Romain Duval, and Dulani Senevirante). The Q&A column looks at "Seven Questions on the Global Housing Markets" (Hites Ahir, Heedon Kang, and Prakash Loungani). September 2014 issue of the Bulletin also includes updates on IMF Working Papers, Staff Discussion Notes, and Recommended Readings from the IMF Bookstore, as well as special announcements on new staff publications and the Fifteenth Annual Jacques Polak Research Conference. Also included is information on the latest issue of “IMF Economic Review” with a link to an article by Paul Krugman.

This paper reexamines the relationship between trade integration and business cycle synchronization (BCS) using new value-added trade data for 63 advanced and emerging economies during 1995–2012. In a panel framework, we identify a strong positive impact of trade intensity on BCS—conditional on various controls, global common shocks and country-pair heterogeneity—that is absent when gross trade data are used. That effect is bigger in crisis times, pointing to trade as an important crisis propagation mechanism. Bilateral intra-industry trade and trade specialization correlation also appear to increase co-movement, indicating that not only the intensity but also the type of trade matters. Finally, we show that dependence on Chinese final demand in value-added terms amplifies the international spillovers and synchronizing impact of growth shocks in China.

The paper uses a combination of micro-level datasets to document the rise of income polarization—what some have referred to as the “hollowing out” of the income distribution—in the United States, since the 1970s. While in the initial decades more middle-income households moved up, rather than down, the income ladder, since the turn of the current century, most of polarization has been towards lower incomes. This result is striking and in contrast with findings of other recent contributions. In addition, the paper finds evidence that, after conditioning on income and household characteristics, the marginal propensity to consume from permanent changes in income has somewhat fallen in recent years. We assess the potential impacts of these trends on private consumption. During 1998-2013, the rise in income polarization and lower marginal propensity to consume have suppressed the level of real consumption at the aggregate level, by about 31⁄2 percent—equivalent to more than one year of consumption.

Is there a minimum tax to GDP ratio associated with a significant acceleration in the process of growth and development? We give an empirical answer to this question by investigating the existence of a tipping point in tax-to-GDP levels. We use two separate databases: a novel contemporary database covering 139 countries from 1965 to 2011 and a historical database for 30 advanced economies from 1800 to 1980. We find that the answer to the question is yes. Estimated tipping points are similar at about 123⁄4 percent of GDP. For the contemporary dataset we find that a country just above the threshold will have GDP per capita 7.5 percent larger, after 10 years. The effect is tightly estimated and economically large.

The Fund has recognized in recent years that one cannot separate issues of economic growth and stability on one hand and equality on the other. Indeed, there is a strong case for considering inequality and an inability to sustain economic growth as two sides of the same coin. Central to the Fund’s mandate is providing advice that will enable members’ economies to grow on a sustained basis. But the Fund has rightly been cautious about recommending the use of redistributive policies given that such policies may themselves undercut economic efficiency and the prospects for sustained growth (the so-called “leaky bucket” hypothesis written about by the famous Yale economist Arthur Okun in the 1970s). This SDN follows up the previous SDN on inequality and growth by focusing on the role of redistribution. It finds that, from the perspective of the best available macroeconomic data, there is not a lot of evidence that redistribution has in fact undercut economic growth (except in extreme cases). One should be careful not to assume therefore—as Okun and others have—that there is a big tradeoff between redistribution and growth. The best available macroeconomic data do not support such a conclusion.

The December 2015 IMF Research Bulletin features a sampling of key research from the IMF. The Research Summaries in this issue look at “The Impact of Deflation and Lowflation on Fiscal Aggregates (Nicolas End, Sampawende J.-A. Tapsoba, Gilbert Terrier, and Renaud Duplay); and “Oil Exporters at the Crossroads: It Is High Time to Diversify” (Reda Cherif and Fuad Hasanov). Mahvash Saeed Qureshi provides an overview of the fifth Lindau Meeting in Economics in “Meeting the Nobel Giants.” In the Q&A column on “Seven Questions on Financial Frictions and the Sources of the Business Cycle, Marzie Taheri Sanjani looks at the driving forces of the business cycle and macroeconomic models. The top-viewed articles in 2014 from the IMF Economic Review are highlighted, along with recent IMF Working Papers, Staff Discussion Notes, and IMF publications.

The IMF Research Bulletin includes listings of recent IMF Working Papers and Staff Discussion Notes. The research summaries in this issue are “Explaining the Recent Slump in Investment” (Mathieu Bussiere, Laurent Ferrara, and Juliana Milovich) and “The Quest for Stability in the Housing Markets” (Hites Ahir). The Q&A column reviews “Seven Questions on Estimating Monetary Transmission Mechanism in Low-Income Countries” (Bin Grace Li, Christopher Adam, and Andrew Berg). Also included in this issue are updates on the IMF’s official journal, the IMF Economic Review, and recommended readings from IMF Publications.