Projectors and linear estimation in general linear models

The paper gives a self-contained account of minimum disper­sion linear unbiased estimation of the expectation vector in a linear model with the dispersion matrix belonging to some, rather arbitrary, set of nonnegative definite matrices. The approach to linear estimation in general linear models recommended here is a direct generalization of some ideas and results presented by Rao (1973, 19 74) for the case of a general Gauss-Markov model

A new insight into the nature of some estimation problems originaly arising in the context of a general Gauss-Markov model as well as the correspondence of results known in the literature to those obtained in the present paper for general linear models are also given. As preliminary results the theory of projectors defined by Rao (1973) is extended.     

Estimation in singular partitioned,reduced or transformed linear models

A singular partitioned linear model, i.e. the singular model comprising the main parameters and the nuisance parameters, can be reduced, or transformed to the form in which only linear functions concerning main parameters are involved. In the paper some properties of the best linear unbiased estimators of these functions following from these models are considered.     

Two-phase nonlinear regression with smooth transition

A method of estimating parameters of twophase nonlinear regression with smooth transition between phases is described. It consists of two stages, both utilizing the least square fit. In the first one, each phase is fitted separately and, simultaneously, a transition point is determined. In the second stage, the two phases are joined smoothly by a proper transition function, which depends on the transition point chosen by the grid search. The practical aspects of the method proposed are demonstrated on the data concerning the soil bulk density in dependence on the soil water content.     

Some methods for constructing efficiency-balanced block designs

Three methods are presented for constructing connected efficiency-balanced block designs from other block designs with the same properties. The resulting designs differ from the original ones in the number of blocks and/or in the number of experimental units and their arrangement, while the number of treatments remains unaltered. Some remarks on the proposed methods of construction refer also to variance-balanced block designs.     

On equalities between BLUES,WLSEs, and SLSEs

Necessary and sufficient conditions for equalities between the best linear unbiased estimator, the weighted least-squares estimator, and the simple least-squares estimator of the expectation vector in a general Gauss-Markoff model are given in some alternative formulations. The main result states, somewhat surprisingly, that the weighted least-squares estimator cannot be identical with the simple least-squares estimator unless they both coincide with the best linear unbiased estimator.     

Approximate confidence intervals for a ratio of two variance components

New approximate confidence intervals for the ratio of two variance components in an unbalanced mixed .linear model with a single set of random effects are proposed. Contrary to the confidence intervals known in the literature the new intervals preserve the confidence coefficient and cover the exact confidence interval which, however, is not easy to establish as it requires the solution of complicated nonlinear equations.     

On nested block designs geometry

Nested block designs and block designs properties such as orthogonality, orthogonal block structure and general balance are examined using the concept of a commutative quadratic subspace and standard properties of orthogonal projectors. In this geometrical context conditions for existence of the best linear unbiased estimators of treatment contrasts are also discussed.     

Forging and sustaining research-minded professionals: teaching undergraduate research through student-community partnerships

The teaching of research is a well-established core component of social work curricula around the world. While educators in social work recognize the value, and need for research they have encountered persistent discomfort and reluctance from students to recognize this need. Practitioners in the field of social work often share this reserve either due to limited self-efficacy with regard to research knowledge and skills or practical constraints. With the growing need for practice-based knowledge, accountability and evidence-based practices to drive outcomes and service effectiveness, it is becoming imperative to not only prepare future social work professionals with the required skill sets but also support current professionals to meet these expectations. This paper showcases a pedagogical endeavor with an undergraduate research course in an American rural university, designed and implemented to create and support research-minded professionals through student–agency research partnerships. Through a collaborative, service-oriented learning, students have gained a new appreciation for research and agency connections while agencies have welcomed the path created to pursue their research agenda. This experience has valuable implications for research capacity building, and for community engaged research empowering future and current professionals to suitably use research toward effective and meaningful service provision.     

Change resistance moderates existence and longevity biases

Evidence has been found for existence and longevity biases—inferences of goodness from prevalence or longevity. We argue these biases actually emerge among change-resisting individuals. Our evidence suggests change-accepting individuals can even demonstrate a reversal of these biases. In two studies, change-resisting individuals’ attitudes were suggestive of existence and longevity biases while change-accepting individuals significantly reversed this pattern by evaluating long-standing or prevalent objects less favorably. Finally, we reanalyzed data from the existence and longevity biases literature previously reported in Social Influence. We found Americans identifying as more Republican—thus theorized as more change-resisting—were those who favored a long-standing practice. Altogether, we argue that existence and longevity biases emerge depending on individuals’ change resistance, indicating an important theoretical expansion.     

Drivers of Exploitation and Inequity in Non‐Timber Forest Products (NTFP) Value Chains: The Case of Indian Bay Leaf in Nepal and India

This article presents the findings of a study that analysed the Indian Bay Leaf (Cinnamomum tamala) Nees and Eberm value chain (VC) in Uttarakhand, India and Udayapur, Nepal. The results show that bay‐leaf VCs are loosely integrated and consist of stakeholders with asymmetrical power relations and different priorities. Traders in India dominate the chains and inappropriate standards lead to the exploitation of small producers and inequity in the chain. Policy measures are suggested for improving co‐ordination and competitiveness in the bay‐leaf VC which could be applied to the NTFP sector as a whole.