Properties of the weighted log‐rank test in the design of confirmatory studies with delayed effects

Proportional hazards are a common assumption when designing confirmatory clinical trials in oncology. This assumption not only affects the analysis part but also the sample size calculation. The presence of delayed effects causes a change in the hazard ratio while the trial is ongoing since at the beginning we do not observe any difference between treatment arms, and after some unknown time point, the differences between treatment arms will start to appear. Hence, the proportional hazards assumption no longer holds, and both sample size calculation and analysis methods to be used should be reconsidered. The weighted log‐rank test allows a weighting for early, middle, and late differences through the Fleming and Harrington class of weights and is proven to be more efficient when the proportional hazards assumption does not hold. The Fleming and Harrington class of weights, along with the estimated delay, can be incorporated into the sample size calculation in order to maintain the desired power once the treatment arm differences start to appear. In this article, we explore the impact of delayed effects in group sequential and adaptive group sequential designs and make an empirical evaluation in terms of power and type‐I error rate of the of the weighted log‐rank test in a simulated scenario with fixed values of the Fleming and Harrington class of weights. We also give some practical recommendations regarding which methodology should be used in the presence of delayed effects depending on certain characteristics of the trial.     

Managing Migration: The Role of Economic Instruments

This paper reviews economic policies and instruments available to the developed countries to reduce unwanted migration from developing countries, not all of which is irregular migration. Countries generally welcome legal immigrants and visitors, try to make it unnecessary for people to become refugees and asylum seekers, and try to discourage, detect, and remove irregular foreigners. There are three major themes: 1. There are as many reasons for migration as there are migrants, and the distinction between migrants motivated by economic and non–economic considerations is often blurred. Perhaps the best analogy is to a river – what begins as one channel that can be managed with a dam can become a series of rivulets forming a delta, making migration far more difficult to manage. 2. The keys to reducing unwanted migration lie mostly in emigration countries, but trade and investment fostered by immigration countries can accelerate economic and job growth in both emigration and immigration countries, and make trading in goods a substitute for economically motivated migration. Trade and economic integration had the effect of slowing emigration from Europe to the Americas, between southern Europe and northern Europe, and in Asian Tiger countries such as South Korea and Malaysia. However, the process of moving toward freer trade and economic integration can also increase migration in the short term, producing a migration hump, and requiring cooperation between emigration and immigration destinations so that the threat of more migration does not slow economic integration and growth. 3. Aid, intervention, and remittances can help reduce unwanted migration, but experience shows that there are no assurances that such aid, intervention, and remittances would, in fact, lead migrants to stay at home. The better use of remittances to promote development, which at US$65 billion in 1999 exceeded the US$56 billion in official development assistance (ODA), is a promising area for cooperation between migrants and their areas of origin, as well as emigration and immigration countries. There are two ways that differences between countries can be narrowed: migration alone in a world without free trade, or migration and trade in an open economy. Migration will eventually diminish in both cases, but there is an important difference between reducing migration pressures in a closed or open world economy. In a closed economy, economic differences can narrow as wages fall in the immigration country, a sure recipe for an anti–immigrant backlash. By contrast, in an open economy, economic differences can be narrowed as wages rise faster in the emigration country. Areas for additional research and exploration of policy options include: (1) how to phase in freer trade, investment, and economic integration to minimize unwanted migration; (2) strategies to increase the job–creating impacts of remittances, perhaps by using aid to match remittances that are invested in job–creating ways.     

Wage and Non-Wage Compensation Among Young Alcoholic and Heavy Drinking Women: A Preliminary Analysis

The association between drinking and selected job characteristics among women aged 24 to 31 is examined. Using the 1989 NLSY, women are classified as alcohol abusers or dependent based on DSM-III-R criteria or as heavy drinkers based on reported frequency of six or more drinks. Heavy drinking is negatively associated with wage and non-wage compensation. These effects diminish when human capital measures are controlled. Current alcoholism and current and past heavy drinking are strongly negatively associated with years of schooling. The association between alcoholism and job compensation and characteristics is not as strong as that seen for heavy drinking. It is not known if this is a consequence of errors in identifying alcoholic women in population-based surveys.     

The Ethnicity of Efficacy: Vietnamese Goddess Worship and the Encoding of Popular Histories

This article examines the reasons for the popularity of spirits of different ethnic backgrounds in the southern Vietnamese plain. The official approach is to induct the cults to these spirits into defence of the nation and its culture, a construct which privileges ethnic Kinh views of history. However, the 'Lady of the Realm', a goddess in the Mekong delta, illustrates the more complex ethnicity of this symbolism. Popular views denying her Khmer origins naturalise the Vietnamese colonisation of Cambodian lands. A preferred lineage in some quarters is to regard her as Cham, a view which disputes a more popular view of her as a Chinese belief, particularly influential in circles where ethnic Chinese business practices have become the norm. This play of interpretations indicates that conventional motifs of cultural resistance or survival are inadequate to understanding religious symbols which speak to the more complex identity of this region of the country.     

The Electoral College and Conflict in American History and Politics

The historical relationship between the electoral college and controversial U.S. presidential elections, specifically with respect to conflict, is examined. The elections of 1800, 1824, 1860, 1876, 1888, 1968, and 2000 are examined. Aside from the 2000 election, there has been essentially no conflict in American history due to the electoral college. The constitutional structure and thinking behind the form of the electoral college is given, with emphasis on the federal aspects of the structure. The current movement to abolish the electoral college in favor of direct popular vote is depicted, along with the arguments against making that change. The conclusion is that we as a nation are far better off to retain the status quo than to make the called-for change.     

‚The Good, the Bad, and the Ugly‘

According to the most influential contribution of recent years to the comparative study of advanced welfare states, Esping-Andersen’s ’Three Worlds of Welfare Capitalism‘, the welfare state basically comes in three variants: as a social-democratic, a conservative, or as a liberal regime. Yet, at a closer look, in particular the ’conservative‘ regime-type represents a highly problematic category. The article claims that the major problems of Esping-Andersen’s typology and theory originate from his sole focus on the class conflict and his neglect of the religious cleavage. Major theoretical contradictions and empirical puzzles of his approach can be solved if we take not only the impact of the catholic social doctrine on the development of the welfare state into account, but consider also the influence of social protestantism, especially that of protestant dissent and of protestant non-conformism. The paper substantiates this claim with data for the early formative period of the welfare state (1890–1920) as well as for the high-time of the welfare state from the 1960s to the 1990s.     

A NOTE ON EVANESCENT PROCESSES

This note examines the connection between μ-invariant measures for the transition function of a continuous-time Markov chain and those of its q-matrix, Q. The major result establishes a necessary and aufficient condition for a convergent μ-invariant measure for Q to be μ-inhant for the minimal transition function, P, under the assumption that P is honest. This corrects Theorem 6 of Vere-Jones (1969) and the first part of Corollary 1 of Pollett (1986), both of which assert that the above conclusion holds in the absence of this condition. The error was pointed out by E.A. van Doom (1991) and the counterexample which be presented provides the basis for the present arguments. In determining where the error occurred in the original proof, we are able to identify a simple sufficient condition for μ-invariance.     

Robustness of a Class of Partial Diallel Cross Designs to the Unavailability of a Complete Block of Observations

Complete and partial diallel cross designs are examined as to their construction and robustness against the loss of a block of observations. A simple generalized inverse is found for the information matrix of the line effects, which allows evaluation of expressions for the variances of the line-effect differences with and without the missing block. A-efficiencies, based on average variances of the elementary contrasts of the line-effects, suggest that these designs are fairly robust. The loss of efficiency is generally less than 10%, but it is shown that specific comparisons might suffer a loss of efficiency of as much as 40%.