Forecasting Recessions Under the Gramm-Rudman-Hollings Law

The targeted deficit reductions of the Gramm-Rudman-Hollings (GRH) law are to be temporarily suspended in case of an official determination that real economic growth either (a) has been less than one percent in the two most recent reported quarters, or (b) is projected to be less than zero in any two consecutive quarters out the next six. This amounts to a particular definition of recession. But business cycles are best identified by the consensus of movements in the principal economic aggregates. Not all recessions are associated with real GNP declining or growing less than 1% for two successive quarters. Also, GNP estimates are subject to long sequences of revisions that are often large. We show that, for these reasons, conditioning a suspension of deficit cuts upon specific changes in preliminary data for real GNP involves very long lags in recognizing recessions. The recessions would be largely over before they were identified. We also show that forecasts of real GNP, based on the consensus among groups of professional forecasters, can reduce these lags considerably. This is so despite the fact that early and accurate predictions of business cycle peaks are rare, and false warnings occur.

The Development and Role of the National Bureau's Business Cycle Chronologies

A working definition, first formulated in the 1920's by Mitchell and revised in the 1940's, has been in use at the National Bureau for over fifty years and is still employed to identify and date business cycles. The NBER historical chronologies for England, France, and Germany as well as the United States have been intensively in economic research and are widely accepted. The U.S. chronology, which is being updated as promptly as the data allow, also have the important practical function of aiding the analysis of current business conditions and forecasting near-term cyclical developments. This paper discusses the main aspects of the NBER concept of business cycles; the early views and developments bearing on the construction of the chronologies; the problems and procedures involved; the characteristics and dependability of the historical reference dates; and the National Bureau's work in this field since World War II. Some recent uses of the U.S. dates to measure the duration, amplitudes, and diffusion of business expansions and contractions are illustrated. Finally, we show and discuss chronologies of growth cycles,' i.e., trend-adjusted business cycles, for 13 countries in the post-World War II period.

Major Changes in Cyclical Behavior

Various structural, institutional, and policy changes have contributed to the evolution of business cycles, since World War II business expansions have been much longer and contractions much shorter than before. Over nearly 200 years of U.S. history expansions have been long relative to contractions when prices had upward secular trends, and shorter when price trends were down. The rising price trend since the 1930's fits this pattern, although we find no association between the rate of inflation during each business cycle and the relative duration of the phases. Shifts in the industrial composition of employment, in labor-force participation, and in the distribution of personal income have all contributed to the post-1945 moderation of cyclical amplitudes. The variability of economic change was low by historical standards in both 1948-69 and 1969-81, although the inflation rate was much higher and real growth on the average lower after 1969. The recent long-term inflation is attributable mainly to the new persistence of upward price movements in business cycle contractions rather than to more rapid price increases during expansions. But prices have always been sensitive to the degree of severity of business contractions, and they still are. The same is true of short-terminterest rates, although they became more sensitive during 1949-82 than before. Despite the deep changes in the economy, many basic characteristics of the business cycle remain unchanged, notably the timing relationships among groups of leading and lagging indicators.

Identifying factors associated with sedentary time after stroke. Secondary analysis of pooled data from nine primary studies.

<p><b>Background</b>: High levels of sedentary time increases the risk of cardiovascular disease, including recurrent stroke.</p> <p><b>Objective</b>: This study aimed to identify factors associated with high sedentary time in community-dwelling people with stroke.</p> <p><b>Methods</b>: For this data pooling study, authors of published and ongoing trials that collected sedentary time data, using the activPAL monitor, in community-dwelling people with stroke were invited to contribute their raw data. The data was reprocessed, algorithms were created to identify sleep-wake time and determine the percentage of waking hours spent sedentary. We explored demographic and stroke-related factors associated with total sedentary time and time in uninterrupted sedentary bouts using unique, both univariable and multivariable, regression analyses.</p> <p><b>Results</b>: The 274 included participants were from Australia, Canada, and the United Kingdom, and spent, on average, 69% (SD 12.4) of their waking hours sedentary. Of the demographic and stroke-related factors, slower walking speeds were significantly and independently associated with a higher percentage of waking hours spent sedentary (p = 0.001) and uninterrupted sedentary bouts of <i>>30</i> and <i>>60 min</i> (p = 0.001 and p = 0.004, respectively). Regression models explained 11–19% of the variance in total sedentary time and time in prolonged sedentary bouts.</p> <p><b>Conclusion</b>: We found that variability in sedentary time of people with stroke was largely unaccounted for by demographic and stroke-related variables. Behavioral and environmental factors are likely to play an important role in sedentary behavior after stroke. Further work is required to develop and test effective interventions to address sedentary behavior after stroke.</p

Halo orbits in cosmological disk galaxies : tracers of information history

We analyze the orbits of stars and dark matter particles in the halo of a disk galaxy formed in a cosmological hydrodynamical simulation. The halo is oblate within the inner ∼20 kpc and triaxial beyond this radius. About 43% of orbits are short axis tubes—the rest belong to orbit families that characterize triaxial potentials (boxes, long-axis tubes and chaotic orbits), but their shapes are close to axisymmetric. We find no evidence that the self-consistent distribution function of the nearly oblate inner halo is comprised primarily of axisymmetric short-axis tube orbits. Orbits of all families and both types of particles are highly eccentric, with mean eccentricity �0.6. We find that randomly selected samples of halo stars show no substructure in “integrals of motion” space. However, individual accretion events can clearly be identified in plots of metallicity versus formation time. Dynamically young tidal debris is found primarily on a single type of orbit. However, stars associated with older satellites become chaotically mixed during the formation process (possibly due to scattering by the central bulge and disk, and baryonic processes), and appear on all four types of orbits. We find that the tidal debris in cosmological hydrodynamical simulations experiences significantly more chaotic evolution than in collisionless simulations, making it much harder to identify individual progenitors using phase space coordinates alone. However, by combining information on stellar ages and chemical abundances with the orbital properties of halo stars in the underlying self-consistent potential, the identification of progenitors is likely to be possible