Optimum designs for parameter estimation in a mixture experiment with two correlated responses

In this paper, we investigate a mixture problem with two responses, which are functions of the mixing proportions, and are correlated with known dispersion matrix. We obtain D- and A-optimal designs for estimating the parameters of the response functions, when none or some of the regression coefficients of the two functions are the same. It is shown that when no prior knowledge about the regression coefficients is available, the D-optimal design is independent of the dispersion matrix, while the A-optimal design depends on it, provided the response functions are of different degree. On the other hand, when some of the regression coefficients are known to be the same for both the functions, the D-optimal design depends on the dispersion matrix when the two response functions are not of the same degree.     

Optimum mixture designs in a restricted region

In a mixture experiment, the response depends on the proportions of the mixing components. Canonical models of different degrees and also other models have been suggested to represent the mean response. Optimum designs for estimation of the parameters of the models have been investigated by different authors. In most cases, the optimum design includes the vertex points of the simplex as support points of the design, which are not mixture combinations in the true non-trivial sense. In this paper, optimum designs have been obtained when the experimental region is an ellipsoidal subspace of the entire factor space which does not cover the vertex points of the simplex.     

D-Optimum Designs for Optimum Mixture in a Quadratic Log Contrast Model

Optimal designs for estimating the optimum mixing proportions in a quadratic mixture model was first investigated by Pal and Mandal (2006). In this article, similar investigation is carried out when mean response in a mixture experiment is described by a quadratic log contrast model. It is found that in a symmetric subspace of the finite dimensional simplex, there exists a D-optimal design that puts weights at the centroid of the sub-space and the vertices of the experimental domain. The optimality is checked by numerical computation using Equivalence Theorem.     

Reorienting Gender and Globalization: Introduction to the Special Issue

The scholarship on gender and globalization has contributed a far more complex picture of the impact of global processes as well as added a crucial gendered perspective on such processes. It has shown us how global processes may reinscribe, alter, and challenge sex/gender orders, which are not necessarily coherent or hegemonic. Yet, we think there is more that gender and globalization scholarship can do to enhance understandings of global processes. We argue that to do so, the literature needs to develop further by overcoming several limitations: (1) an understanding of gender that still tends to reflect the binary sex/gender arrangements common to Western societies, while failing to address the influence of colonial histories and postcolonial states (Roberts and Connell, Feminist Theory 17(2): 135–140, 2016; Sinha 2012); (2) a gender asymmetry, i.e., a disproportionate focus on women; (3) a narrow set of issues that come under its analytical lens; (4) a primary focus outside the US; and finally (5) a gender division of intellectual labor in which primarily feminists who identify as women study gender and globalization while those who identify as men, feminist or otherwise, tend to study a gender blind globalization. In this introduction, we examine the development of the gender and globalization literature, discuss how the articles in this special issue expand on it, and conclude with future directions for this burgeoning field.     

Optimum Mixture Design for the Detection of Synergistic Effects

In mixture experiments, optimal designs for the estimation of parameters, both linear and non-linear, have been discussed by several authors. Optimal designs for the estimation of a subset of parameters have also been investigated. However, designs for testing the effects of certain factors and interactions have been studied only in the context of response surface models. In this article, we attempt to find the optimum design for testing the presence of synergistic effects in a mixture model. The classical F-test has been considered and the optimum design has been obtained so as to maximize the power of the test. It is observed that the barycenters are necessarily the support points of the trace-optimal design.     

“Consent is Good,Joyous, Sexy”: A banner campaign to market consent to college students

ABSTRACT

Objective: This study assessed the recall of, reaction to, and understanding of a brief campus banner campaign promoting consent in sexual relationships, and determined whether campaign exposure was associated with subsequent engagement in activities related to sexual assault education, awareness, and prevention. Participants: A stratified random sample of 1,200 undergraduates was recruited during fall of 2010; 628 (52.3%) participated. Methods: To account for history and maturation, an experimental research design was employed with an online survey. Results: Direct and indirect campaign exposure was associated with increased action. Students expressed primarily positive reactions to and appeared to understand the consent message. The campaign appealed to and was associated with increased activity among a wide range of students with one exception: a negative effect was observed for business students. Conclusions: Colorful banners with pithy, upbeat messages hold promise for engaging undergraduates in conversations and proactive activities related to sexual assault prevention.     

Young people as global citizens: negotiation of youth civic participation in adult-managed online spaces

With the proliferation of new media technologies, online spaces for civic engagement are being used as new sites by the young people for enacting global citizenship. Some of these online civic spaces are managed by parent organizations and guide the participants towards accomplishing goals that align with the institutional policies. We use Stuart Hall’s theoretical framework to ground the two methods we used for empirical research- textual analysis of the selected online spaces and in-depth interviews with young bloggers. Our analysis shows how negotiated reading of the encoded messages on the online platforms for youth civic engagement marks a political moment of signification in which there lies a possibility of challenging the dominance of the adult centered notions of civic engagement. Shelat’s online civic culture framework [2014. “Citizens, Global Civic Engagement on Online Platforms: Women as Transcultural Citizens.” Dissertation] helped us examine how these managed platforms encode global citizenship with pre-designed participatory practices that reinforce the hegemonic definition of youth political participation. Interviews of young bloggers on two online global spaces foreground the process of negotiation with the dominant definitions and the use of decoding strategies to create scope for subjective, more local definitions, as well as practices of civic engagement and global citizenship. Though literature suggests that adult-management of online youth spaces perpetuate a gap between the adult-centric notions of participation and the youth oriented ideas of civic engagement, our study reveals that the young participants find ways of articulating their ideas and enter these spaces with plans on how to fulfill their civic goals.     

Optimum mixture designs for the log-logistic dose–response model with mixture of two similar compounds

The article studies the log-logistic class of dose–response bioassay models in the binomial set-up. The dose is identified by the potency adjusted mixing proportions of two similar compounds. Models for both absence and presence of interaction between the compounds have been considered. The aim is to investigate the D- and D_s-optimal mixture designs for the estimation of the full set of parameters or for the estimation of potency for a best guess of the parameter values. We also indicate how to find the optimal design to estimate the mixing proportions at which the probability of success attains a given value in the absence of the interaction effect.