Prehistoric human impact on the environment in the upland North American Southwest

Some early Anasazi (prehistoric Puebloan) agricultural practices tended to be land-extensive and made substantial impact on the forests, primarily through clearing by burning. Later agriculture tended to be more land-intensive, but longer duration occupations by larger populations also had significant local effects on the forests, through both clearing for fields and through intensive harvest of firewood. Strategies of early Anasazi agriculture that resulted in forest depletion probably also tended to maximize the power output of the economic systems, and therefore must have had considerable selective value. Depletion of various wild resources was an important impetus to culture change, leading, in conjunction with population growth, to more intensive farming practices, and contributing to the tendency to aggregate in large villages at various times in the prehistoric period.     

Trends in Late-Life Activity Limitations in the United States: An Update From Five National Surveys

This article updates trends from five national U.S. surveys to determine whether the prevalence of activity limitations among the older population continued to decline in the first decade of the twenty-first century. Findings across studies suggest that personal care and domestic activity limitations may have continued to decline for those ages 85 and older from 2000 to 2008, but generally were flat since 2000 for those ages 65–84. Modest increases were observed for the 55- to 64-year-old group approaching late life, although prevalence remained low for this age group. Inclusion of the institutional population is important for assessing trends among those ages 85 and older in particular.     

Flourishing Across Europe: Application of a New Conceptual Framework for Defining Well-Being

Governments around the world are recognising the importance of measuring subjective well-being as an indicator of progress. But how should well-being be measured? A conceptual framework is offered which equates high well-being with positive mental health. Well-being is seen as lying at the opposite end of a spectrum to the common mental disorders (depression, anxiety). By examining internationally agreed criteria for depression and anxiety (DSM and ICD classifications), and defining the opposite of each symptom, we identify ten features of positive well-being. These combine feeling and functioning, i.e. hedonic and eudaimonic aspects of well-being: competence, emotional stability, engagement, meaning, optimism, positive emotion, positive relationships, resilience, self esteem, and vitality. An operational definition of flourishing is developed, based on psychometric analysis of indicators of these ten features, using data from a representative sample of 43,000 Europeans. Application of this definition to respondents from the 23 countries which participated in the European Social Survey (Round 3) reveals a four-fold difference in flourishing rate, from 41% in Denmark to less than 10% in Slovakia, Russia and Portugal. There are also striking differences in country profiles across the 10 features. These profiles offer fresh insight into cultural differences in well-being, and indicate which features may provide the most promising targets for policies to improve well-being. Comparison with a life satisfaction measure shows that valuable information would be lost if well-being was measured by life satisfaction. Taken together, our findings reinforce the need to measure subjective well-being as a multi-dimensional construct in future surveys.     

Designs foe phase i cancer clinical trials with differentiation of graded toxicity

For phase I cancer clinical trials, toxicity is a major concern. Commonly, toxicity is categorized to five levels of severity. In addition to the traditional standard dose-escaiation design, the Continual Reassessment Method (CRM) provides a promising alternative to estimate the maximum tolerated dose of a drug. However, in both standard design (STD) and CRM, the severity level of toxicity on grade 3/4 of a previous patient's response would not be a differentiated factor for the next dose level assignment. In this study, we extend the procedure incorporating the idea of unequal weights on the assessments of grade 3 and grade 4 toxicity in the dose escalation. The simulation results show that the proposed extended procedures by taking the impact of grade 4 toxicity into account, both for STD and CRM, reduce the chance of recommendation to the higher dose levels. Similar trends are observed for patient allocation to the higher levels. Additionally, for CRM which performs more accurately on the estimation of maximum tolerated dose (MTD), the proposed extended CRM maintains the same characteristic.     

Analyzing survival data in conjunction with time-dependent surrogate endpoints in clinical trials

Current survival techniques do not provide a good method for handling clinical trials with a large percent of censored observations. This research proposes using time-dependent surrogates of survival as outcome variables, in conjunction with observed survival time, to improve the precision in comparing the relative effects of two treatments on the distribution of survival time. This is in contrast to the standard method used today which uses the marginal density of survival time, T. only, or the marginal density of a surrogate, X, only, therefore, ignoring some available information. The surrogate measure, X, may be a fixed value or a time-dependent variable, X(t). X is a summary measure of some of the covariates measured throughout the trial that provide additional information on a subject's survival time. It is possible to model these time-dependent covariate values and relate the parameters in the model to the parameters in the distribution of T given X. The result is that three new models are available for the analysis of clinical trials. All three models use the joint density of survival time and a surrogate measure. Given one of three different assumed mechanisms of the potential treatment effect, each of the three methods improves the precision of the treatment estimate.     

A Useful Property of Some Symmetric Statistics

The distributions of some statistics arising from the comparison of two populations share a common structure. Consequences of this structure are derived and their usefulness indicated. The examples of statistics to which the theory applies include various correlation coefficients.     

Estimation bias of different design and analytical strategies in dual-frame telephone surveys: an empirical evaluation

Dual-frame survey designs have become increasingly popular in large-scale telephone surveys. This is due to the lack of coverage of the traditional landline survey design and the escalating use of cell phones in recent years. Several estimation strategies have been proposed and their properties have been discussed under ideal scenarios, including pseudo-maximum-likelihood estimation, single-frame estimation, and simple composite estimation [C.J. Skinner and J.N.K. Rao, Estimation in dual frame surveys with complex designs, J. Am. Statist. Assoc. 91 (1996), pp. 349–356; S.L. Lohr and J.N.K. Rao, Inference from dual frame surveys, J. Am. Statist. Assoc. 95 (2000), pp. 271–280]. In practice, estimation in dual-frame telephone surveys is vulnerable to biases and errors (e.g. inaccessibility, topic/mode salience, and measurement error). The investigation of the performance of popular dual-frame estimation methods is scarce in real and less ideal scenarios. Through an innovatively designed simulation study, we compare the estimation bias under different sampling designs with various estimation strategies. To reduce bias, different raking strategies are compared. Simulated scenarios incorporating sampling costs are examined for practical considerations. Overall, the cell phone-only design yields results with the least bias and variance. When accurate covariate information is available for post-stratification, raking estimates from the cell phone-any design also perform very well. We also provide SAS macros for this simulation evaluation upon request. Survey practitioners can fine-tune the parameters based on their prior knowledge of the target population and run the simulation under different scenarios to gain more insights into how to optimally design and analyse telephone surveys.     

Test of a Trust and Confidence Model in the Applied Context of Electromagnetic Field (EMF) Risks

Trust is an important factor in risk management. There is little agreement among researchers, however, on how trust in risk management should be studied. Based on a comprehensive review of the trust literature a "dual-mode model of social trust and confidence" is proposed. Trust and confidence are separate but, under some circumstances, interacting sources of cooperation. Trust is based on value similarity, and confidence is based on performance. According to our model, judging similarity between an observer's currently active values and the values attributed to others determines social trust. Thus, the basis for trust is a judgment that the person to be trusted would act as the trusting person would. Interpretation of the other's performance influences confidence. Both social trust and confidence have an impact on people's willingness to cooperate (e.g., accept electromagnetic fields or EMF in the neighborhood). The postulated model was tested in the applied context of EMF risks. Structural equation modeling procedures and data from a random sample of 1,313 Swiss citizens between 18 and 74 years old were used. Results indicated that after minor modifications the model explained the data very well. In the applied context of EMF risks, both trust and confidence had an impact on cooperation. Results suggest that the dual-mode model of social trust and confidence could be used as a common framework in the field of trust and risk management. Practical implications of the results are discussed.