A Bootstrap Stationarity Test for Predictive Regression Invalidity

In order for predictive regression tests to deliver asymptotically valid inference, account has to be taken of the degree of persistence of the predictors under test. There is also a maintained assumption that any predictability in the variable of interest is purely attributable to the predictors under test. Violation of this assumption by the omission of relevant persistent predictors renders the predictive regression invalid, and potentially also spurious, as both the finite sample and asymptotic size of the predictability tests can be significantly inflated. In response, we propose a predictive regression invalidity test based on a stationarity testing approach. To allow for an unknown degree of persistence in the putative predictors, and for heteroscedasticity in the data, we implement our proposed test using a fixed regressor wild bootstrap procedure. We demonstrate the asymptotic validity of the proposed bootstrap test by proving that the limit distribution of the bootstrap statistic, conditional on the data, is the same as the limit null distribution of the statistic computed on the original data, conditional on the predictor. This corrects a long-standing error in the bootstrap literature whereby it is incorrectly argued that for strongly persistent regressors and test statistics akin to ours the validity of the fixed regressor bootstrap obtains through equivalence to an unconditional limit distribution. Our bootstrap results are therefore of interest in their own right and are likely to have applications beyond the present context. An illustration is given by reexamining the results relating to U.S. stock returns data in Campbell and Yogo (2006 Campbell, J. Y. and Yogo, M. (2006), “Efficient Tests of Stock Return Predictability,” Journal of Financial Economics, 81, 27–60.[Crossref], [Web of Science ®] , [Google Scholar]). Supplementary materials for this article are available online.     

The Modeling and Seasonal Adjustment of Weekly Observations

Several important economic time series are recorded on a particular day every week. Seasonal adjustment of such series is difficult because the number of weeks varies between 52 and 53 and the position of the recording day changes from year to year. In addition certain festivals, most notably Easter, take place at different times according to the year. This article presents a solution to problems of this kind by setting up a structural time series model that allows the seasonal pattern to evolve over time and enables trend extraction and seasonal adjustment to be carried out by means of state-space filtering and smoothing algorithms. The method is illustrated with a Bank of England series on the money supply.     

Whither Risk Assessment: New Challenges and Opportunities a Third of a Century After the Red Book

Six multi‐decade‐long members of SRA reflect on the 1983 Red Book in order to examine the evolving relationship between risk assessment and risk management; the diffusion of risk assessment practice to risk areas such as homeland security and transportation; the quality of chemical risk databases; challenges from other groups to elements at the core of risk assessment practice; and our collective efforts to communicate risk assessment to a diverse set of critical groups that do not understand risk, risk assessment, or many other risk‐related issues. The authors reflect on the 10 recommendations in the Red Book and present several pressing challenges for risk assessment practitioners.     

What’s disability got to do with it? Changing constructions of Oscar Pistorius before and after the death of Reeva Steenkamp

Traditionally disability has been viewed in the popular imagination as either a highly positive or highly negative phenomenon. Disability and disabled people deserve to be seen in an integrated, holistic way and to have recognised as much diversity as characterises the human condition. The recent case of Oscar Pistorius fatally shooting Reeva Steenkamp has highlighted this tendency. Before this incident, Pistorius’ disability was viewed in a predominantly positive light. He had been described as a ‘supercrip’ who had, despite his physical impairments, ‘overcome’ his mobility limitations and was consequently attributed heroic status by some. However, after this fatal incident, the portrayal of Pistorius’ disability has, perhaps inevitably, shifted. This paper will offer possible psychosocial reasons for this tendency to view disability in a binary way.     

Health care applications of complexity science. Life at the edge of chaos

The authors explore complexity science, a relatively new field of inquiry, which holds for both clinicians and health care leaders the real possibility of stimulating fresh insights and approaches to health and medical care-both its provision and its organization. Two case studies are presented to illustrate how complexity theory can provide health care leaders with a new perspective on how to address the myriad challenges they confront daily: (1) a patient with dissociative identity disorder; and (2) a physician task group charged to advise on hospital medical staff reorganization and governance. These case studies help clinicians and leaders of health care organizations understand how complexity: (1) may be relevant, even helpful, as they consider difficult challenges in both patient and organizational management; and (2) might emerge as a synthesizing force as they face the extraordinarily complicated task of jointly creating integrated health care systems. A resource section is provided for those who may wish to further pursue the topic.     

A General Formula for Valuing Defaultable Securities

Previous research has shown that under a suitable no‐jump condition, the price of a defaultable security is equal to its risk‐neutral expected discounted cash flows if a modified discount rate is introduced to account for the possibility of default. Below, we generalize this result by demonstrating that one can always value defaultable claims using expected risk‐adjusted discounting provided that the expectation is taken under a slightly modified probability measure. This new probability measure puts zero probability on paths where default occurs prior to the maturity, and is thus only absolutely continuous with respect to the risk‐neutral probability measure. After establishing the general result and discussing its relation with the existing literature, we investigate several examples for which the no‐jump condition fails. Each example illustrates the power of our general formula by providing simple analytic solutions for the prices of defaultable securities.     

Multilevel models for repeated binary outcomes: attitudes and voting over the electoral cycle

Models for fitting longitudinal binary responses are explored by using a panel study of voting intentions. A standard multilevel repeated measures logistic model is shown to be inadequate owing to a substantial proportion of respondents who maintain a constant response over time. A multivariate binary response model is shown to be a better fit to the data.     

Has East Germany Overtaken West Germany? Recent Trends in Order‐Specific Fertility

Some 20 years after reunification, the contrast between East and West Germany offers a natural experiment for studying the degree of persistence of Communist-era family patterns, the effects of economic change, and fertility postponement. After reunification, period fertility rates plummeted in the former East Germany to record low levels. Since the mid-1990s, however, period fertility rates have been rising in East Germany, in contrast to the nearly constant rates seen in the West. By 2008, the TFR of East Germany had overtaken that of the West. We explore why fertility in East Germany is higher than in West Germany, despite unfavorable economic circumstances in the East. We address this and related questions by (a) presenting an account of the persisting East/West differences in attitudes toward and constraints on childbearing, (b) conducting an order-specific fertility analysis of recent fertility trends, and (c) projecting completed fertility for the recent East and west German cohorts. In addition to using the Human Fertility Database, perinatal statistics allow us to calculate a tempo-corrected TFR for East and West Germany.