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161.
Two-stage designs offer substantial advantages for early phase II studies. The interim analysis following the first stage allows the study to be stopped for futility, or more positively, it might lead to early progression to the trials needed for late phase II and phase III. If the study is to continue to its second stage, then there is an opportunity for a revision of the total sample size. Two-stage designs have been implemented widely in oncology studies in which there is a single treatment arm and patient responses are binary. In this paper the case of two-arm comparative studies in which responses are quantitative is considered. This setting is common in therapeutic areas other than oncology. It will be assumed that observations are normally distributed, but that there is some doubt concerning their standard deviation, motivating the need for sample size review. The work reported has been motivated by a study in diabetic neuropathic pain, and the development of the design for that trial is described in detail. 相似文献
162.
John Ermisch Diego Gambetta Heather Laurie Thomas Siedler S. C. Noah Uhrig 《Journal of the Royal Statistical Society. Series A, (Statistics in Society)》2009,172(4):749-769
Summary. We measure trust and trustworthiness in British society with a newly designed experiment using real monetary rewards and a sample of the British population. The study also asks the typical survey question that aims to measure trust, showing that it does not predict 'trust' as measured in the experiment. Overall, about 40% of people were willing to trust a stranger in our experiment, and their trust was rewarded half of the time. Analysis of variation in the trust behaviour in our survey suggests that trusting is more likely if people are older, their financial situation is either 'comfortable' or 'difficult' compared with 'doing alright' or 'just getting by', they are a homeowner or they are divorced, separated or never married compared with those who are married or cohabiting. Trustworthiness also is more likely among subjects who are divorced or separated relative to those who are married or cohabiting, and less likely among subjects who perceive their financial situation as 'just getting by' or 'difficult'. We also analyse the effect of attitudes towards risks on trust. 相似文献
163.
164.
For a dose finding study in cancer, the most successful dose (MSD), among a group of available doses, is that dose at which the overall success rate is the highest. This rate is the product of the rate of seeing non-toxicities together with the rate of tumor response. A successful dose finding trial in this context is one where we manage to identify the MSD in an efficient manner. In practice we may also need to consider algorithms for identifying the MSD which can incorporate certain restrictions, the most common restriction maintaining the estimated toxicity rate alone below some maximum rate. In this case the MSD may correspond to a different level than that for the unconstrained MSD and, in providing a final recommendation, it is important to underline that it is subject to the given constraint. We work with the approach described in O'Quigley et al. [Biometrics 2001; 57(4):1018-1029]. The focus of that work was dose finding in HIV where both information on toxicity and efficacy were almost immediately available. Recent cancer studies are beginning to fall under this same heading where, as before, toxicity can be quickly evaluated and, in addition, we can rely on biological markers or other measures of tumor response. Mindful of the particular context of cancer, our purpose here is to consider the methodology developed by O'Quigley et al. and its practical implementation. We also carry out a study on the doubly under-parameterized model, developed by O'Quigley et al. but not 相似文献
165.
John Ermisch 《Journal of population economics》2008,21(4):827-853
The paper presents a model of a non-resident father’s child support and contact with his child, which combines the public
good treatment of “child quality” with “trade” in father–child contact time in a setting of non-cooperative interaction. It
predicts that father’s income and mother’s non-labour income should have exactly the same effect on the frequency of father–child
contact if he chooses to make lump sum payments to the mother. If he does not or there is a binding child support payment
order, they have effects opposite in direction. A higher binding support order reduces father–child contact but may well raise
“child quality”.
相似文献
John ErmischEmail: |
166.
Population and Environment - This article is a synopsis of a UN study, with emphasis on Italy and the United States. In March, 2000, the United Nations Population Division published a 143-page... 相似文献
167.
John Stillwell Martin Bell Marcus Blake Oliver Duke-Williams Phil Rees 《Journal of Population Research》2001,18(1):19-39
This paper explores the impact of net migration in Australia and the United Kingdom using measures of migration effectiveness
computed from period-age migration data for four consecutive five-year periods. Results reported in Part 1 of this paper (Stillwellet al. 2000) suggest that while the overall effectiveness of net migration at the scale of city regions has declined over the twenty-year
period in both countries, important geographical variations are evident. Part 2 considers how patterns of migration effectiveness
vary by age and presents a single classification of all the city regions on the basis of age-specific effectiveness. More
detailed analysis includes spatial patterns for particular age groups and net migration profiles of selected regions. Cohort
effects are shown to be important for explaining changes between time periods in these regions. 相似文献
168.
Abstract The highly volatile auction system in Australia accounts for 85 percent of ex‐farm wool sales, with the remainder sold by forward contract, futures, and other hedging methods. In this article, against the background of an extensive literature on price risk strategies, we investigate title behavioral factors associated with producers' adoption of price risk‐management strategies (specifically futures and forward contracts) for selling wool. This research presents a behavioral model based on Diffusion of Innovations, the Theory of Reasoned Action, and the Theory of Planned Behavior. We found that the auction system is used as a price risk‐management tool because other selling methods are considered more risky. We also report on a curious relationship between risk and complexity in terms of wool producers' intentions to use forward contracts. We explored sociological factors in conjunction with focus‐group data in an attempt to understand this relationship. This exercise yielded some interesting findings on the impact that trust, habit, social cohesion, and networks have on decision making in the rural community. The significance of this article lies in its application of core sociological theory in a new research context: the Australian wool industry. 相似文献
169.
Variability has been demonstrated to be an operant dimension of behavior (Neuringer, 2002; Page & Neuringer, 1985). Recently, lag schedules have been used to demonstrate operant variability of verbal behavior in persons with a diagnosis of autism (e.g., Lee, McComas, & Jawor, 2002). The current study evaluated the effects of a Lag 1 schedule on the vocal variability of 2 nonverbal children with a diagnosis of autism. Results showed systematic increases in variability during the Lag 1 schedule. Implications of lag schedules for speech and language training are discussed. 相似文献
170.
Scholars have grown concerned that the commercialization of academic science is increasing secrecy at the expense of cooperation and information sharing. Using data from comparable surveys of academic scientists in three fields (experimental biology, mathematics, and physics), we test whether scientists have become more competitive and more secretive over the last 30 years. We also use the recent survey to test a multivariate model of the effects of scientific competition and commercialization (patenting, industry funding, and industry collaboration) on scientific secrecy. We find that secrecy has increased, and has increased particularly for experimental biologists. Only 13 percent of experimental biologists in 1998 felt safe discussing their ongoing research with all others doing similar work. Our multivariate analysis shows that this secrecy is most related to concerns about being anticipated (scientific competition). We find that patenting is associated with increased secrecy among mathematicians and physicists, but not for experimental biologists. We find that industry funding is associated with more secrecy, while industry collaboration is associated with less secrecy, across fields. Our results suggest that the recent concern over increasing scientific secrecy has merit. However, this increased secrecy seems to result from a combination of increasing commercial linkages and increased pressures from scientific competition. Our research highlights the central role that scientists' competition for priority plays in the system of science and that, while such competition spurs effort, it also produces negative effects that recent trends toward commercialization of academic science seem to be exacerbating. 相似文献