Periodic Properties of Interpolated Time Series

Although linearly interpolated series are often used in economics, little has been done to examine the effects of interpolation on time series properties and on statistical inference. We show that linear interpolation of a trend tationary series superimposes a ‘periodic’ structure on the moments of the series. Using conventional time series methods to make inference about the interpolated series may therefore be invalid. Also, the interpolated series may exhibit more shock persistence than the original trend stationary series.Linear Interpolation, Trend-Stationary Series, Shock Persistence, Periodic Properties of Time Series

On the Typical Spectral Shape of an Economic Variable

In a classic article, Granger (1966) asserted that most economic time series measured in level have spectra that exhibit a smooth declining shape with considerable power at very low frequencies. There has been no systematic attempt to examine Granger,s assertion with international data. We estimate output level spectra for 58 countries, divided into developed, high-income developing, and low-income developing groups. We find the shapes of the estimated spectra to be strikingly similar to Granger"s typical shape, particularly for the developed countries.Spectral Analysis, Spectral Shape, Output Level, OECD, Developing Countries.

Testing for speculative bubbles in stock prices

A modification of Kenneth West's method for investigating speculative bubbles in stock prices, in which a direct test of the "no bubble" hypothesis is applied to long-term annual U.S. stock-market data.Stock - Prices

International Evidence on Output Fluctuation and Shock Persistence

We estimate output growth rate spectra for 58 countries. The spectra exhibit diverse shapes. To study the sources of this diversity, we estimate the short-run, business cycle, and long-run frequency components of the sampled series. For most OECD countries the bulk of the spectral mass is in the business cycle frequency band, and the magnitude of this cyclical component increases with income. For the developing countries, however, the spectral mass is not concentrated in the business cycle frequency band, and the income-cycle relationship is not as strong. We also estimate two frequency domain measures of shock persistence and find both measures to vary considerably across countries, with the U.S. having the lowest estimates. For the OECD countries most of the variation in the variance ratio statistic appears to be explained by the variation in the long-term growth component.Business Cycles, Developing Countries, OECD Countries, Output Fluctuation, Output Growth, Shock Persistence, Spectral Analysis, Frequency Domain, Short Run, Long Run, Frequency Component, Income-Cycle Relationship, Variance Ratio Statistic

International Evidence on Output Fluctuation and Shock Persistence

We estimate output growth rate spectra for 58 countries. The spectra exhibit diverse shapes. To study the sources of this diversity, we estimate the short-run, business cycle, and long-run frequency components of the sampled series. For most OECD countries the bulk of the spectral mass is in the business cycle frequency band, and the magnitude of this cyclical component increases with income. For the developing countries, however, the spectral mass is not concentrated in the business cycle frequency band, and the income-cycle relationship is not as strong. We also estimate two frequency domain measures of shock persistence and find both measures to vary considerably across countries, with the U.S. having the lowest estimates. For the OECD countries most of the variation in the variance ratio statistic appears to be explained by the variation in the long-term growth component.-Business Cycles, Developing Countries, OECD Countries, Output Growth, Shock Persistence, and Spectral Analysis.

Interpolation and Shock Persistence of Prewar U.S. Macroeconomic Time Series: A Reconsideration

The U.S. prewar output series exhibit smaller shock-persistence than postwar-series. Some studies suggest that this may be due to linear interpolation used to generate missing prewar data. Monte Carlo simulations that support this view generate large standard-errors, making such inference imprecise. We assess analytically the effect of linear interpolation on a nonstationary process. We find that interpolation indeed reduces shock-persistence, but the interpolated series can still exhibit greater shock-persistence than a pure random walk. Moreover, linear interpolation makes the series periodically nonstationary, with parameters of the data generating process and the length of the interpolation time-segments affecting shock-persistence in conflicting ways

Speculative bubbles and the cross-sectional variation in stock returns

Evidence suggests that rational, periodically collapsing speculative bubbles may be pervasive in stock markets globally, but there is no research that considers them at the individual stock level. In this study we develop and test an empirical asset pricing model that allows for speculative bubbles to affect stock returns. We show that stocks incorporating larger bubbles yield higher returns. The bubble deviation, at the stock level as opposed to the industry or market level, is a priced source of risk that is separate from the standard market risk, size and value factors. We demonstrate that much of the common variation in stock returns that can be attributable to market risk is due to the co-movement of bubbles rather than being driven by fundamentals

Rational speculative bubbles: an empirical investigation of the London Stock Exchange

In recent years, a sharp divergence of London Stock Exchange equity prices from dividends has been noted. In this paper, we examine whether this divergence can be explained by reference to the existence of a speculative bubble. Three different empirical methodologies are used: variance bounds tests, bubble specification tests, and cointegration tests based on both ex post and ex ante data. We find that, stock prices diverged significantly from their fundamental values during the late 1990's, and that this divergence has all the characteristics of a bubble