Any series of observations ordered along a single dimension, such as time, may be thought of as a time series. The emphasis in time series analysis is on studying the dependence among observations at different points in time. What distinguishes time series analysis from general multivariate analysis is precisely the temporal order imposed on the observations. Many economic variables, such as GNP and its components, price indices, sales, and stock returns are observed over time. In addition to being interested in the contemporaneous relationships among such variables, we are often concerned with relationships between their current and past values, that is, relationships over time.

Time Series Analysis

The central claim in this paper is that by explicitly introducing costs of international trade (narrowly, transport costs, but more broadly, tariffs, nontariff barriers, and other trade costs), one can go far toward explaining a great number of the main empirical puzzles that international macroeconomists have struggled with over twenty-five years. Our approach elucidates J. McCallum's home-bias-in-trade puzzle, the Feldstein-Horioka saving-investment puzzle, the French-Poterba equity-home-bias puzzle, and the Backus-Kehoe-Kydland consumption-correlations puzzle. That one simple alteration to an otherwise canonical international macroeconomic model can help substantially to explain such a broad range of empirical puzzles, including some that previously seemed intractable, suggests a rich area for future research. We also address a variety of international pricing puzzles, including the purchasing-power-parity puzzle emphasized by Rogoff, and what we term the exchange-rate disconnect puzzle. The latter cat...

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The Six Major Puzzles in International Macroeconomics: Is There a Common Cause?

This paper investigates the impact of tax changes on economic activity. We use the narrative record, such as presidential speeches and Congressional reports, to identify the size, timing, and principal motivation for all major post war tax policy actions. This analysis allows us to separate legislated changes into those taken for reasons related to prospective economic conditions and those taken for more exogenous reasons. The behavior of output following these more exogenous changes indicates that tax increases are highly contractionary. The effects are strongly significant, highly robust, and much larger than those obtained using broader measures of tax changes. (JEL E32, E62, H20, N12) Tax changes have been a major public policy issue in recent years. The tax cuts of 2001 and 2003 were passed amid firestorms of debate about their likely effects. Some policymakers claimed that the cuts would both stimulate the economy in the short run and increase normal output in the long run. Others argued that they would raise interest rates and lower confidence and thereby reduce output in both the short run and the long run. That views of the effects of tax changes vary so radically largely reflects the fact that measuring these effects is very difficult. Tax changes occur for many reasons. Some legislated tax changes are passed for philosophical reasons or to reduce an inherited budget deficit. Others are passed because the economy is weak and predicted to fall further, or because a war is in progress and government spending is rising. And many tax changes are not legislated at all, but occur automatically because the tax base varies with the overall level of income, or because of changes in stock prices, inflation, and other nonpolicy forces. Because the factors that give rise to tax changes are often correlated with other developments in the economy, disentangling the effects of the tax changes from the effects of these underlying factors is inherently difficult. There is pervasive omitted variable bias in any regression of output on an aggregate measure of tax changes. This paper suggests one way of dealing with this omitted variable bias. There exists a vast narrative record describing the history and motivation of tax policy changes. We first use this narrative history to separate legislated tax changes from those arising from nonpolicy develop ments. We then use the information on motivation to separate the legislated tax changes into those that are likely to be contaminated by other developments affecting output, and those that can legitimately be used to measure the macroeconomic effects of tax changes. Finally, we use the legitimate observations to derive estimates of the effects of tax changes on output that are likely to be less biased than previous estimates. Section I of the paper elaborates on the conceptual framework for this study. It emphasizes that what we seek to identify from the narrative record are tax changes that are not systematically

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The Macroeconomic Effects of Tax Changes: Estimates Based on a New Measure of Fiscal Shocks

This paper studies how the Hodrick-Prescott filter should be adjusted when changing the frequency of observations. It complements the results of Baxter and King (1999) with an analytical analysis, demonstrating that the filter parameter should be adjusted by multiplying it with the fourth power of the observation frequency ratios. This yields an HP parameter value of 6.25 for annual data given a value of 1600 for quarterly data. The relevance of the suggestion is illustrated empirically.

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On Adjusting the Hodrick-Prescott Filter for the Frequency of Observations

In recent years a widespread consensus has emerged about the necessity of establishing bridges between the quantitative and the qualitative approaches to empirical research in political science. In this article, we discuss the use of the synthetic control method (Abadie and Gardeazabal, 2003; Abadie, Diamond, and Hainmueller, 2010) as a way to bridge the quantitative/qualitative divide in comparative politics. The synthetic control method provides a systematic way to choose comparison units in comparative case studies. This systematization opens the door to precise quantitative inference in small-sample comparative studies, without precluding the application of qualitative approaches. That is, the synthetic control method allows researchers to put \qualitative esh on quantitative bones" (Tarrow, 1995). We illustrate the main ideas behind the synthetic control method with an application where we study the economic impact of the 1990 German reunication in West Germany.

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Comparative Politics and the Synthetic Control Method

This paper estimates the dynamic effects of changes in taxes in the United States. We distinguish between changes in personal and corporate income taxes and develop a new narrative account of federal tax liability changes in these two tax components. We develop an estimator which uses narratively identified tax changes as proxies for structural tax shocks and apply it to quarterly post-WWII data. We find that short run output effects of tax shocks are large and that it is important to distinguish between different types of taxes when considering their impact on the labor market and on expenditure components.

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The Dynamic Effects of Personal and Corporate Income Tax Changes in the United States

This paper studies how the HP-Filter should be adjusted, when changing the frequency of observations It complements the results of Baxter and King (1999) with an analytical analysis, demonstrating that the filter parameter should be adjusted by multiplying it with the fourth power of the observations frequency ratios This yields an HP parameter value of 625 for annual data given a value of 1600 for quarterly data The relevance of the suggestion is illustrated empirically

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On Adjusting the HP-Filter for the Frequency of Observations

We show the importance of a dynamic aggregation bias in accounting for the PPP puzzle. We prove that the aggregate real exchange rate is persistent because its components have heterogeneous dynamics. Established time series and panel methods fail to control for this. Using Eurostat data, we find that when heterogeneity is taken into account, the estimated persistence of real exchange rates falls dramatically. Its half-life, for instance, may fall to as low as eleven months, significantly below the "consensus view" of three to five years.

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PPP Strikes Back: Aggregation And the Real Exchange Rate

We provide empirical evidence on the dynamic effects of tax liability changes in the United States. We distinguish between surprise and anticipated tax changes using a timing-convention. We document that pre-announced but not yet implemented tax cuts give rise to contractions in output, investment and hours worked while real wages increase. In contrast, there are no significant anticipation effects on aggregate consumption. Implemented tax cuts, regardless of their timing, have expansionary and persistent effects on output, consumption, investment, hours worked and real wages. Results are shown to be very robust. We argue that tax shocks are empirically important impulses to the U.S. business cycle and that anticipation effects have been important during several business cycle episodes.

https://papers.ssrn.com/sol3/Delivery.cfm/SSRN_ID1681302_code1543148.pdf?abstractid=1681302&mirid=1

Morten O. Ravn

Papers

On Adjusting the Hodrick-Prescott Filter for the Frequency of Observations

The Dynamic Effects of Personal and Corporate Income Tax Changes in the United States

On Adjusting the HP-Filter for the Frequency of Observations

PPP Strikes Back: Aggregation And the Real Exchange Rate

Empirical Evidence on the Aggregate Effects of Anticipated and Unanticipated U.S. Tax Policy Shocks