解释世界储蓄

International Finance Discussion Papers ISSN 1073-2500 (Print)ISSN 2767-4509 (Online) Number 1416 August 2025 Explaining World Savings Colin Caines and Amartya Lahiri NOTE: International Finance Discussion Papers (IFDPs) are preliminary materials circulated to stimu-late discussion and critical comment.The analysis and conclusions set forth are those of the authors anddo not indicate concurrence by other members of the research staff or the Board of Governors. Referencesin publications to the International Finance Discussion Papers Series (other than acknowledgement) shouldbe cleared with the author(s) to protect the tentative character of these papers. Recent IFDPs are availableon the Web at www.federalreserve.gov/pubs/ifdp/. This paper can be downloaded without charge from theSocial Science Research Network electronic library at www.ssrn.com. Explaining World Savings Colin Caines∗and Amartya Lahiri† ‡ Abstract Saving rates are significantly different across countries and remain different for longperiods of time. This paper provides an explanation for this phenomenon. We formalizea model of a world economy comprised of open economies inhabited by heterogeneousagents endowed with recursive preferences. Our assumed preferences imply increasingmarginal impatience of agents as their consumption rises relative to average consump-tion of a reference group. Using measured productivity as the sole exogenous driver,we show that the model can not only reproduce the sustained long run differences inaverage saving rates across countries, but also provides a good fit to the time seriesbehavior of saving observed in the data. Keywords:World savings, recursive preferences JEL Classification:E2, F3, F4 1Introduction Data on the world saving distribution reveals that cross-country differences in saving ratesare significant and persistent. This is problematic for the standard model with time-additivepreferences.Without equal rates of time preference, the asymptotic distribution of worldwealth is typically degenerate under additively separable preferences.While models withequal rates of time preference but cross-country differences in demographics and productivityhave had some success in accounting for part of the cross-country dispersion in saving rates,a substantial amount of variation still remains unexplained in these models. This paper provides an alternative explanation for the observed saving patterns.Weformalize a model of the world economy that is comprised of open economies inhabited byinfinitely-lived agents.Our main point of departure from the standard exogenous growthneoclassical model is that we endow agents with recursive preferences.1 Specifically, wefollow Farmer and Lahiri (2005) and use a modified version of recursive preferences.Thekey implication of the Farmer-Lahiri specification is that it generates a determinate steadystate wealth distribution within a growing world economy, a feature that typical models withrecursive preferences cannot generate.2 One might of course consider the issue of balanced growth to be irrelevant to under-standing savings behavior. We however believe that the inconsistency of standard recursivepreferences with balanced growth is problematic if one’s goal is to explain saving rates. Inparticular, given the constancy of both long run average growth rates and saving rates for most groups of countries (regions or continents), understanding long run patterns of savingswould appear to be intrinsically linked to long run steady state dynamics. As is well known,the Kaldor growth facts are quite stark in suggesting balanced growth to be a robust featureof long run growth. Hence, we feel that any model attempting an explanation of dispersionsin long run saving rates across countries should be consistent with balanced growth. We follow Farmer and Lahiri (2005) and construct a model of recursive utility in whichagents care aboutrelativeconsumption.We assume that preferences are described by anaggregator that contains current consumption, future utility, and a time-varying factor that isexternal to the agent but grows at the common growth rate in a balanced growth equilibrium.This time dependence allows for preferences to exhibit increasing marginal impatience, whichis a necessary condition for a non-degenerate asymptotic wealth distribution.A positiveproductivity shock in our model induces a rise in saving which ultimately reverts back to itsprior level due to the increasing marginal impatience of agents as their wealth rises relativeto world wealth, thereby preserving a determinate asymptotic wealth distribution. Equallyimportantly, this specification implies that different preferences induce different steady stateconsumption-to-wealth ratios of different agents.This implies that countries operating inthe same world bond market and facing a common world interest rate have different steadystate saving rates. Can the modified recursive preferences of Farmer and Lahiri (2