Optimum treatment allocation for dual-objective clinical trials with binary outcomes

A common problem in randomized controlled clinical trials is the optimal assignment of patients to treatment protocols, The traditional optimal design assumes a single criterion, although in reality, there are usually more than one objective in a clinical trial. In this paper, optimal treatment allocation schemes are found for a dual-objective clinical trial with a binary response. A graphical method for finding the optimal strategy is proposed and illustrative examples are discussed.     

Optimal two-point designs for the michaelis-menten model with heteroscedastic errors

We construct D-optimal designs for the Michaelis-Menten model when the variance of the response depends on the independent variable. However, this dependence is only partially known. A Bayesian approacn is used to find an optimal design by incorporating the prior lnformation about the variance structure. We demonstrate the method for a class of error variance structures and present efficiencies of these optimal designs under prior mis-specifications. In particular, we show that an erroneous assumption on the variance structure for the Michaelis-Menten model can have serious consequences.     

Adaptive grid semidefinite programming for finding optimal designs

We find optimal designs for linear models using a novel algorithm that iteratively combines a semidefinite programming (SDP) approach with adaptive grid techniques. The proposed algorithm is also adapted to find locally optimal designs for nonlinear models. The search space is first discretized, and SDP is applied to find the optimal design based on the initial grid. The points in the next grid set are points that maximize the dispersion function of the SDP-generated optimal design using nonlinear programming. The procedure is repeated until a user-specified stopping rule is reached. The proposed algorithm is broadly applicable, and we demonstrate its flexibility using (i) models with one or more variables and (ii) differentiable design criteria, such as A-, D-optimality, and non-differentiable criterion like E-optimality, including the mathematically more challenging case when the minimum eigenvalue of the information matrix of the optimal design has geometric multiplicity larger than 1. Our algorithm is computationally efficient because it is based on mathematical programming tools and so optimality is assured at each stage; it also exploits the convexity of the problems whenever possible. Using several linear and nonlinear models with one or more factors, we show the proposed algorithm can efficiently find optimal designs.     

A semi-infinite programming based algorithm for finding minimax optimal designs for nonlinear models

Minimax optimal experimental designs are notoriously difficult to study largely because the optimality criterion is not differentiable and there is no effective algorithm for generating them. We apply semi-infinite programming (SIP) to solve minimax design problems for nonlinear models in a systematic way using a discretization based strategy and solvers from the General Algebraic Modeling System (GAMS). Using popular models from the biological sciences, we show our approach produces minimax optimal designs that coincide with the few theoretical and numerical optimal designs in the literature. We also show our method can be readily modified to find standardized maximin optimal designs and minimax optimal designs for more complicated problems, such as when the ranges of plausible values for the model parameters are dependent and we want to find a design to minimize the maximal inefficiency of estimates for the model parameters.     

Immigration,living arrangement and the poverty risk of older adults in Hong Kong

Using 2011 census data, this study investigated how living arrangement affects disparities in poverty between older adults (aged 65 and older) who migrated to Hong Kong from Mainland China and those who were born in Hong Kong. Our sample consisted of 29,987 immigrants and 9,398 natives, all of whom were ethnic Chinese and living in Hong Kong at the time of the census. We found higher poverty rates among older immigrants than among natives, a disparity that persisted even after adjusting for living arrangement, human capital characteristics, assimilation‐related variables, household composition and demographic characteristics. We also found that living arrangement moderated the impact of immigrant status on the poverty risk among older adults, and that the impact was due mainly to the number of earners in the household. The implications of our results with respect to poverty among older adults and anti‐poverty measures are discussed.     

Development of Financial Capacity in Adolescents

This study aims to check whether the framework of developing financial capacity of adolescents is similar as that of college students, as well as whether adolescence, compared to college age, is the better age for objective financial knowledge to trigger the positive cycle of developing financial capacity. Using a convenience sample of 967 adolescent students from five Hong Kong secondary schools, this study conducted structural equation modeling to evaluate the development of financial capacity. Both subjective and objective financial knowledge in adolescents can be internalized into financial self-beliefs. Subsequently, these self-beliefs influence their financial behavior. The effect of objective financial knowledge on the financial self-beliefs, which is weak for college students, was much stronger for adolescents. The framework of developing financial capacity of adolescents is similar as that of college students. Adolescence, compared to college age, is the better age for objective financial knowledge to trigger the positive cycle of developing financial capacity.     

Testing an environmental framework for understanding public relations practitioners’ orientation toward relationship management

This study offers an alternative conceptual framework for an integrated understanding of public relations practice globally. It investigates the relationships between political, economic, and media constructs and relationship management in public relations by building upon an environmental framework for understanding public relations. Based on a survey of public relations practitioners in Singapore, this study positions relationship management as a conceptual locus for public relations theory and practice. Four environmental variables—perceptions of the degree of democracy in the political system, level of economic development, level of economic freedom, and level of media freedom—are found to be associated with public relations practitioners’ orientation toward relationship management, based on Hon and Grunig’s relationship management scale.     

Birth order matters: the effect of family size and birth order on educational attainment

Using the British Household Panel Survey, we investigate if family size and birth order affect children’s subsequent educational attainment. Theory suggests a trade-off between child quantity and “quality” and that siblings are unlikely to receive equal shares of parental resources devoted to children’s education. We construct a new birth order index that effectively purges family size from birth order and use this to test if siblings are assigned equal shares in the family’s educational resources. We find that the shares are decreasing with birth order. Ceteris paribus, children from larger families have less education, and the family size effect does not vanish when we control for birth order. These findings are robust to numerous specification checks.