An Improvement of the Westlake Symmetric Confidence Interval

A common statistical method for assessing bioequivalence of two formulations of a chemical substance is the symmetric confidence interval of WESTLAKE (1972). As mentioned by WEST -LAKE (1981) and SCHUIRMAN (1981) a more powerful method consists of two one-sided t-tests. An (1-α)-confidence interval consistent with the two one-sided t-tests procedure is given by [min(α, 0), max (0, b)] where [a, b] is the conventional (1–2α)-confidence interval of the t-test. This “central” confidence interval is always a strict subset of the symmetric confidence interval and thus has more power in proving bioequivalence. The central confidence interval has properties comparable with those of the conventional one-sided confidence intervals.     

Aggregate index of social–environmental sustainability to evaluate the social–environmental quality in a watershed in the Southern Amazon

The purpose of this study was to build an aggregate index of social–environmental sustainability derived from incorporation of indicators of the quality of soil, water, and vegetation, and social organization and socioeconomic variables, in order to assess the overall social–environmental quality in a micro watershed in the Southern Amazon. From a population of 105 family production units 56 were randomly selected for evaluation of indicators of the quality of soil and water as well as for conducting interviews to evaluate the farmers’ perception of soil, water, and vegetation quality and also of socioeconomic aspects of agroecosystems. The aggregate index built from social–environmental sustainability indicators shows that the selected indicators were adequate for describing social–environmental quality and confirms the hypothesis that the studied micro-watershed in the southern edge of the Amazon is in a state of collapse, and is socially and environmentally degraded.     

Estimating Location Parameters Using Censored Rank Statistics

In this paper censored data rank location estimators are obtained by using censored one-sample rank test statistics of the location parameter and censored two-sample rank test statistics of the shift of location parameter. Also, methods for constructing censored small sample confidence intervals and asymptotic confidence intervals for the location are considered. Generalizations of the solutions from uncensored one-sample and two-sample rank tests are utilized.     

A Method for Analyzing Nonlinear Models When the Data are from a Split-plot or Repeated Measures Design

Statistical methods are described which can be used to compare treatments where the response model is nonlinear and the experimental design includes split-plots or repeated measures. The nonlinear analysis of covariance is described for a two-way treatment structure in a split-plot design structure, the usual split-plot experimental design. Evaluating heat tolerance in common beans as a function of temperature is used as an example to demonstrate the methodology.     

Emergy-based indicators of regional environmental sustainability: A case study in Shanwei,Guangdong, China

Understanding which factors mainly affect the environmental sustainability of a Region is a very crucial concern for many Chinese planners and policy-makers. In this study, the emergy accounting method is applied to the production and consumption activities of the city of Shanwei, a seaside urban area in Guangdong region, China. The emergy method provides a comprehensive assessment of a system, by generating a consistent set of indicators capable to capture the dynamics of the system as a whole and its efficiency in converting resources into an economic product and welfare. At the same time, the approach is capable to provide details about a system's performance over time, its use of renewable versus nonrenewables sources, local versus imported, concentrated versus dispersed and finally labor intensive versus fuel intensive processes. The main local renewable and nonrenewable emergy flows supporting the investigated area were included in the accounting, together with the flows of imported energy, goods, machinery, labor and services. Coal plays a crucial role for electricity generation, industrial uses, but also gasoline and diesel for transport affect the overall sustainability to a non-negligible extent. An Emergy Sustainability Indicator (ESI) of the local economic and social system is calculated and compared with the average value of the Chinese economy, based on the assumption that a process or system is unsustainable if it contributes to lower the overall sustainability of the region or country. This is quantified by the requirement that always must be ESI_local ≧ ESI_country. Results confirm that the most crucial factor for this region sustainability is the use of coal as a non-renewable and imported energy source. The calculated emergy indicators translate into a set-aside buffer land demand capable to mitigate, dilute, and uptake the environmental impact of human-dominated activities. Unfortunately, such buffer land demand is much higher than the land actually available. As a result, both the ESI-based sustainability equation as well as the lack of support land make the city's production and consumption patterns unsustainable and call for different lifestyles and environmental policies.     

Asymptotic Interval Estimation of Some Cause-Specific Mortality Risk Measures in Epidemiologic Studies

The present paper describes the algebraic and statistical relationships between the population-based mortality risk measures, the Standardized Mortality Ratio (SMR) and the Standardized Risk Ratio (SRR), and their respective proportional mortality-based counterparts, the internally and externally Standardized Proportional Mortality Ratios (SPMR, S_ePMR). The paper shows, how under some reasonable assumptions, asymptotically precise inferences about population-based risk measures can be made from studies of proportional mortality. Through application of the asymptotic multivariate normal approximation to the multinomial distribution, shortest confidence intervals for the relative SMR (RSMR) involving the corresponding SPMR are constructed for any cause of death. This same technique is also used to construct asymptotic prediction intervals about the cause-specific S_ePMR which, with high probability, contains the corresponding relative SRR (RSRR). The utility of the proportional mortality measures SPMR and S_ePMR as estimators of the corresponding cause-specific risks RSMR and RSRR in occupational epidemiologic research is empirically evaluated using data from two recent occupational cohort studies. Asymptotic Bonferroni type simultaneous inferential techniques are also developed for these measures which facilitate the assessment of overall risk in the presence of several competing factors.     

Sustainable ecosystem management using optimal control theory: part 2 (stochastic systems)

Sustainable development of ecosystems through external ecosystem management is assuming importance for the environmentalists. To that effect, previous work by the authors looked at the option of manipulating population dynamics of the species in an ecosystem to achieve sustainability. Fisher information is used as the quantifying measure of sustainability and optimal control theory is used to derive the control profiles. However, that work considered only deterministic systems. Uncertainty being prevalent in all systems, particularly in natural systems, this paper extends that work to analyse uncertain systems. Predator-prey models are used to model the species populations and different control philosophies are compared. Ito mean reverting process is used to model the stochastic process, and stochastic maximum principle is used to derive the control profiles. The results for the objective of FI variance minimization qualitatively agree with those for the deterministic system, while the results for the FI maximization objective differ. It is observed that the instability associated with the FI maximization objective for deterministic systems is absorbed by the noise introduced by the uncertainty. Quantitatively, it is observed that the degree of uncertainty, along with its presence, is also important to identify the most appropriate management strategy.     

A method for estimating the numbers of synonymous and nonsynonymous substitutions per site

A method for estimating the numbers of synonymous (Ks) and nonsynonymous (Ka) substitutions per site is proposed. The method is based on the Li's (J Mol. Evol. 36:96–99, 1993) and Pamilo and Bianchi's (Mol. Biol. Evol. 10:271–281, 1993) method, but a putative source of bias is solved. It is proposed that the number of synonymous substitutions that are actually transitions or transversions should be computed by separating the twofold degenerate sites into two types of sites, 2S-fold and 2V-fold, where only transitional and transversional substitutions are synonymous, respectively. Kimura's (J. Mol. Evol. 16:111–120, 1980) two-parameter correcting method for multiple substitutions at a site is then applied using the overall observed synonymous transversion frequency to estimate both the numbers of synonymous transversional (Bs) and transitional (As) substitutions per site. This approach, therefore, also minimizes stochastic errors. Computer simulations indicate that the method presented gives more accurate Ks and Ka estimates than the aforementioned methods. Furthermore, the obtention of confidence intervals for divergence estimates by computer simulation is proposed.