Global Versus Local Shocks in Micro Price Dynamics

A number of recent papers point to the importance of distinguishing between the price reaction to micro and macro shocks in order to reconcile the volatility of individual prices with the observed persistence of aggregate inflation. We emphasize instead the importance of distinguishing between global and local shocks. We exploit a panel of 276 micro price levels collected on a semi-annual frequency from 1990 to 2010 across 88 cities in 59 countries around the world, that enables us to distinguish between different types (local and global) of micro and macro shocks. We find that global shocks have more persistent effects on prices as compared to local ones e.g. prices respond faster to local macro shocks than to global micro ones, implying that the relatively slow response of prices to macro shocks documented in recent studies comes from global rather than local sources. Global macro shocks have the most persistent effect on prices, with the majority of goods and locations sharing a single source of trend over time stemming from these shocks. Finally, both local macro and local micro shocks are associated with relatively fast price convergence. How fast do prices adjust to changes in economic conditions? The answer is crucial in assessing the real effects of nominal shocks, for instance. The literature provides conflicting answers: whereas aggregate price indices have been found to be very persistent, more recent work starting with Bils and Klenow (2004) showed that individual prices adjust frequently. The implication that monetary policy might as a result be less effective than previously thought, has been challenged more recently. Boivin et al. (2009) attempt to resolve the micro-macro puzzle while retaining the importance of monetary policy by distinguishing between the (sluggish) response of individual prices to macroeconomic shocks common to every sector or product, and their (rapid) response to microeconomic shocks specific to a sector or product. Our paper emphasizes the distinction between global shocks common to every location worldwide, and local shocks specific to a location. We show that this distinction is much more striking and no less informative for price-setting models, than the macro-micro split considered in previous work. In fact, we find that the speed of price adjustment in response to local macro shocks or local micro shocks is relatively fast in both cases. At the same time, the price persistence associated with global versus local shocks of any type differs substantially. For both macro and micro shocks alike, local components are associated with much less persistence than global ones. Considering only one type of micro or macro shock would consequently hide the heterogeneity we observe in their effects and lead to misleading inferences about the relative persistence of local macro shocks (typically monetary ones) in micro prices. Based on our findings, price-setting theory models should not include as high a degree of price rigidity in response to local macro shocks as that implied in some of the earlier empirical work. At the same time, our work suggests the need for open economy price-setting theory models consistent with slow response of prices to global micro shocks and persistent price effects of international macro shocks. Our analysis relies on a panel of 276 micro price levels collected from 1990 to 2010 at a semi-annual frequency across 88 cities in 59 countries across the world. This dataset is non-standard and was especially compiled for us by the Economist Intelligence Unit (EIU) at a semiannual frequency for the complete untypically large sample of international locations. The March and September dates for gathering these semi-annual data are specifically designed to avoid standard sales seasons. In addition, EIU correspondents are specifically instructed to take regular retail prices and not to take sale prices. These sampling facts suggest that our price data are not as prone to include temporary price changes, shown by Nakamura and Steinsson (2008) to bias results towards finding more rapid price adjustment. This is important for the inferences we can draw about the speed of price adjustment in response to local shocks for instance. The three dimensions of our panel---time, location and individual product---allow us to decompose the dynamics of the common currency micro price-level for each product in a given location at a given date into four different components: (1) a global macro component common to every good in every location, capturing for example global oil shocks; (2) a global micro component specific to a good and common to every location, related for instance to technology shocks specific to a product but common across the globe; (3) a local macro component specific to a location and common to every good, related for example to monetary policy; and (4) a local micro or idiosyncratic component specific to a good and a location, capturing for instance the idiosyncrasy of weather conditions facing vineyards in a certain location. We obtain convergence rates specific to each component allowing for different speeds of price adjustment to these, our notion of price adjustment speed being the time it takes for prices to fully adjust to a shock. While ignoring the global-local distinction our data would imply that (similar to past research on the micro-macro gap) macro shocks are more persistent than micro ones with convergence rate estimates implying half-lives of 21 months versus 13 months respectively, decomposing macro and micro shocks into their global and local components reveals a different more precise picture. Local micro shocks are the most rapidly corrected ones, followed by local macro shocks, and global micro shocks. More precisely, local micro shocks have a half-life estimate of about 7 months. The reaction to local macro shocks is somewhat more persistent with a half-life of 10 months, while global micro shocks have a half-life that is about twice as long at 18 months. The latter three components of international prices are mean-reverting on average, but this does not apply to all relative prices for all goods or locations. The response of prices to global macro shocks is found to be permanent so that international prices share this single global stochastic trend which is the main factor behind the observed drift in price levels. Furthermore, we find that the global macro and micro components together account for half of the time-series volatility in prices in this sample. The above findings taken together suggest that global shocks cannot be ignored when analyzing the sources of persistence and volatility of prices. Our results confirm that prices react differently to different types of shocks, but stress that sorting shocks by geographic distance (global vs local) leads to more striking differences than sorting shocks by mere economic distance (macro vs micro). The observed differences in persistence of the different price components could stem from differences in the persistence of the shocks driving the processes associated with these components rather than from differences in the reaction of prices to these shocks. We thus investigate further by considering the link between persistence and volatility of the price components. If persistence of the shocks themselves was the main driver of the observed persistence in prices, then we would expect to see a positive relation between own persistence and volatility. The estimated link between these turns out to be either negative or statistically indistinguishable to zero. This leads us to infer that price adjustment to different types of conditions does not stem from the mere persistence of the shocks. The link between persistence and volatility provides us with a couple of additional new facts. First, more volatility in micro conditions is associated with slower adjustment of prices, hence more persistent relative price distortions, in response to changes in macro conditions. Likewise, more volatility in local conditions is associated with slower price adjustment, hence more persistent relative price distortions, in response to changes in global conditions, with this link more than twice as large as the respective micro-macro link. We propose that decomposing macro and micro shocks into finer categories provides a new more precise tool for gauging models of price-setting. The persistence associated with each of these components and its relation with volatility of the different components, provide new facts that price-setting models should be able to rationalize. First, in light of the importance of the global or international dimension, it would be useful to have open economy price-setting models that can rationalize differences in the speed of adjustment to global versus local shocks in addition to macro versus micro shocks. These models should be able to explain why these differences are more striking when shocks are classified with respect to geographic distance (global vs local) rather than mere economic distance (macro vs micro). Second, models of price-setting should be able to cope with the estimated sign and size of the link between local volatility and the rate of price adjustment in response to global shocks. Again, they should also be able to explain why the volatility in local conditions seems to be more detrimental to the adjustment to global conditions, as compared to the effect of volatility in micro conditions for the adjustment to macro conditions. One possibility would be to resort to models of endogenous imperfect perception of shocks, in the spirit of the recent contributions of Reis (2006), MaÃÂkowiak and Wiederholt (2009), Woodford (2009) or Alvarez et al. (forthcoming), where the relative cost of observing global conditions would be greater than the one associated with monitoring local ones, and more so than the relative cost of observing macro conditions exceeds that for micro ones. Similarly, in the context of these models, the loss of processing capacities due to volatility in local conditions could be more detrimental to the monitoring of global conditions, as compared to the loss of processing capacities due to volatility in micro conditions for the monitoring of macro conditions. Rational inattention models are thus a natural candidate to consider for understanding our results. Yet another theoretical possibility would be to rely on labor market segmentation arguments, in the spirit of Carvalho and Lee (2010). Here, the segmentation would need to be greater between countries than within them in the same manner (but more so) that labor segmentation is greater across sectors than within them. However, this framework would also need to incorporate a link between volatility of shocks and persistence of price reactions. Our results on the differential response of prices to different types of shocks extend Clark (2006), Boivin et al. (2009), and MaÃÂkowiak et al. (2009), to a global environment. These papers bridge the gap between measured persistence of macro price indices and the frequent adjustment observed in micro prices. In their setup, a macro shock is common to every sector in the US, potentially encompassing a shock common to every country worldwide (our global macro shock) and a shock specific to the US (our local macro shock). Likewise, their sectoral shock can be made of a worldwide sectoral shock (our global micro shock) and a US sector-specific one (our local micro shock). Our work points to the importance of disentangling global and local components to understand price dynamics. No study of micro price levels has looked at this global/local decomposition of micro and macro shocks. We show that whereas global macro shocks are highly persistent, prices react to local macro shocks much faster than to global micro ones. By contrast, Boivin et al. (2009) find that sectoral prices adjust sluggishly to macro shocks but rapidly to micro ones, a result that has in turn spurred a debate on what theoretical model of price-setting could rationalize such different response of individual prices to different types of shocks. In their own words, their "main finding is that disaggregated prices appear sticky in response to macroeconomic and monetary disturbances, but flexible in response to sector-specific shocks" and that "many prices fluctuate considerably in response to sector-specific shocks, but they respond only sluggishly to aggregate macroeconomic shocks such as monetary policy shocks". To the extent that country-specific monetary policy is part of our local macro component, we find that it has much less persistent effects than in Boivin et al. (2009). Prices respond almost twice as fast to local macro shocks as they do to global micro ones. This also contrasts with the finding of a rapid adjustment to micro shocks in Boivin et al. (2009). The subset of our results that pertains to local micro and local macro shocks contributes to yet another line of research; the literature on international price comparisons. Until recently, international price differences were considered to be very persistent at the aggregate level. Deviations from PPP have a half-life of several years as documented in the surveys by Rogoff (1996) and Obstfeld and Rogoff (2000). The survey by Goldberg and Knetter (1997) stresses that the persistence is of comparable order when one considers deviations from the LOP using relatively aggregated sectoral price indices. Instead, the recent evidence relying on micro-data, such as Goldberg and Verboven (2005) using European car prices, Crucini and Shintani (2008) using annual EIU prices, and Broda and Weinstein (2008) or Burstein and Jaimovich (2009) using barcode prices, is that the persistence of LOP deviations is reduced sharply when based on micro prices with higher comparability across locations. Our estimated half-lives are even lower than in the recent micro-price literature on LOP deviations, in part due to the use of semiannual prices and a broader sample of locations across the world as compared to the previous studies. Although the scope of our paper is broader, to the extent that a subset of our results relates to the LOP literature discussed above they are also relevant for the Bergin et al. (2011) argument that the differential importance and persistence of (local) macro versus (local) micro shocks for LOP deviations can reconcile the macro with the micro evidence for international price convergence rates estimates. They show that macro shocks that dominate at the aggregate level are less volatile and have much greater persistence than idiosyncratic shocks at the individual good level that dominate micro prices. We estimate a more persistent response of individual prices to local macro shocks than to idiosyncratic ones in most cases. However, both responses are relatively fast and not always that different except for developed countries. Thus, our results suggest that the micro/macro gap between fast convergence in deviations from the LOP (micro) and the very persistent deviations from PPP (macro) cannot be entirely resolved by distinguishing between (local) macro and (local) micro shocks in the LOP as there is typically not that much more persistence in local macro shocks as compared to local micro ones. Apart from the much more general sample across (developed and developing) countries and goods (traded and non-traded), and the longer time span being considered in our paper, one factor driving differences in estimates for the local micro and local macro components in the two papers, is that Bergin et al. (2011) use the US as the comparison point relative to which to construct LOP deviations. Choosing a particular location as the comparison point introduces the statistical properties characterizing it into the deviations from the LOP for every other location. Instead, we choose to compare prices to the average across locations so that our findings do not depend on choosing a particular country as the comparison point. Finally, our findings do not depend on using the US dollar as the numeraire currency. Converting prices to the same currency is necessary for comparison.