We propose a survey weighted quadratic inference function method for the analysis of data collected from longitudinal surveys, as an alternative to the survey weighted generalized estimating equation ...method. The procedure yields estimators of model parameters, which are shown to be consistent and have a limiting normal distribution. Furthermore, based on the inference function, a pseudolikelihood ratio type statistic for testing a composite hypothesis on model parameters and a statistic for testing the goodness of fit of the assumed model are proposed. We establish their asymptotic distributions as weighted sums of independent chi‐squared random variables and obtain Rao‐Scott corrections to those statistics leading to a chi‐squared distribution, approximately. We examine the performance of the proposed methods in a simulation study.
The cytoplasmic male sterile line system comprising CRMS 32A and its maintainer line CRMS 32B is a popular choice for the development of new hybrids in India as CRMS 32A, having Kalinga 1 cytoplasm ...(other than WA), is a viable alternative to WA cytoplasm. However, both lines are susceptible to bacterial blight (BB), a major disease on rice. As enhancement of host plant resistance is the most effective and economical strategy to control this disease, four resistance genes (Xa4, xa5, xa13, and Xa21) were transferred from a BB pyramid line of IR64, into the A and B lines using a marker-assisted backcrossing (MAB) breeding strategy. During the transfer of genes into CRMS 32B, foreground selection was applied using markers associated with the genes, and plants having resistance alleles of the donor, are selected. Selection for morphological and quality traits was practiced to select plants similar to the recurrent parent. The four gene and three gene pyramid lines exhibited high levels of resistance against the BB pathogen when challenged with eight virulent isolates. Using genome wide based SSR markers for background selection, pyramids having >95% of the recurrent parent genome were identified. With CRMS 32B gene pyramid as donor, the four resistance genes were transferred into the A line through repeated backcrosses and the A line pyramids also exhibited high level of resistance against BB. Through a combination of selection at phenotypic and molecular levels, four BB resistance genes were successfully introduced into two parental lines (CRMS 32 B and A) of Rajalaxmi, an elite popular hybrid. The pyramided B lines did exhibit high levels of resistance against BB. Selection for morphological and quality traits and background selection hastened the recovery of the recurrent parent genome in the recombinants. Through repeated backcrosses, all the four resistance genes were transferred to CRMS 32A and test crosses suggest that the maintenance ability of the improved CRMS 32B lines is intact. These improved maintainer and CMS lines can directly be used in hybrid rice breeding and the new hybrids can play an important role in sustainable rice production in India.
DECT: A Novel Window in Gout Imaging Bajad, Shruti; Tanna, Dhaval; Durga Rao Yadavalli, J N ...
Journal of the Association of Physicians of India,
06/2023, Volume:
71, Issue:
6
Journal Article
The widely used Elbers–Lanjouw–Lanjouw (ELL) method of estimating complex parameters for areas with small sample sizes uses a fitted nested-error model based on survey data to create simulated ...censuses of the variable of interest. The complex parameters obtained from each simulated censuses are then averaged to get the estimate. An empirical best (EB) method, under the nested-error model with normal errors, is significantly more efficient, in terms of mean square error (MSE), than the ELL method when the normality assumption holds. However, it can perform poorly in terms of MSE when the model errors are not normally distributed. We relax normality by assuming skew-normal errors, derive EB estimators, and study their MSE relative to EB based on normality and ELL. We propose bootstrap methods for MSE estimation. We also study an improvement to ELL by conditioning on the area random effects and without parametric assumptions on the errors.
Robust small area estimation Sinha, Sanjoy K.; Rao, J. N. K.
Canadian journal of statistics,
September 2009, Volume:
37, Issue:
3
Journal Article
Peer reviewed
Small area estimation has received considerable attention in recent years because of growing demand for small area statistics. Basic area-level and unit-level models have been studied in the ...literature to obtain empirical best linear unbiased prediction (EBLUP) estimators of small area means. Although this classical method is useful for estimating the small area means efficiently under normality assumptions, it can be highly influenced by the presence of outliers in the data. In this article, the authors investigate the robustness properties of the classical estimators and propose a resistant method for small area estimation, which is useful for downweighting any influential observations in the data when estimating the model parameters. To estimate the mean squared errors of the robust estimators of small area means, a parametric bootstrap method is adopted here, which is applicable to models with block diagonal covariance structures. Simulations are carried out to study the behaviour of the proposed robust estimators in the presence of outliers, and these estimators are also compared to the EBLUP estimators. Performance of the bootstrap mean squared error estimator is also investigated in the simulation study. The proposed robust method is also applied to some real data to estimate crop areas for counties in Iowa, using farm-interview data on crop areas and LANDSAT satellite data as auxiliary information. L'estimation de petits domaines a reçu considérablement d'attention ces dernières années en raison de la demande croissante de statistiques régionales. Les modèles au niveau des domaines et des unités ont déjà été étudiés dans la littérature et les meilleurs estimateurs linéaires sans biais empiriques (EBLUP) pour les petits domaines ont été obtenus. Quoique cette méthode classique est utile pour estimer les moyennes régionales de façon efficace sous l'hypothèse de normalité, ses résultats sont grandement influencés par la présente de données aberrantes. Dans cet article, les auteurs étudient les propriétés de robustesse des estimateurs classiques et ils proposent une méthode robuste pour l'estimation de petits domaines qui diminue le poids associé aux observations influentes lors de l'estimation des paramètres du modèle. Afin d'estimer l'erreur quadratique moyenne des estimateurs robustes des moyennes régionales, une méthode d'auto-amorçage paramétrique est utilisée. Cette méthode peut être utilisée aux modèles dont la structure de covariance est bloc diagonale. Des simulations sont faites pour étudier le comportement des estimateurs robustes proposés en présence de valeurs aberrantes et aussi pour les comparer aux estimateurs EBLUP. La performance de l'estimateur "boostrap" de l'erreur quadratique moyenne est aussi étudiée dans cette étude de simulations. Cette méthode robuste est appliquée à l'estimation de la superficie des cultures pour les comtés de l'Iowa en se basant sur des entrevues au niveau des fermes et en utilisant les données provenant du satellite LANDSAT comme information auxiliaire.
We prepared two new superhydrophobic functionalized coordination polymers (SFCPs) Zn4(OH)2(BTMB)2(4,4′-Bipy)2∞ ⊃ solvent, 1, and Cd4(OH)2(BTMB)2(4,4′-Bipy)3∞ ⊃ solvent, 2, by solvothermal methods. ...For 1, the single-crystal XRD structure revealed that it contains two crystallographically distinct Zn 2+ ions with two different types of coordination geometries of 4 and 6, exhibiting a unique superhydrophobic behavior with microporosity. Compound 1 exhibits superhydrophobicity with a contact angle of 155.5° (at 30 °C), which is stable even at high temperatures, whereas for the SFCP 2, all of the Cd 2+ ions have only 6-coordination and exhibit a superhydrophobic character at room temperature with a contact angle of 156.7°(at 30 °C). However, surprisingly, this superhydrophobic character is stable only up to 60 °C, above which it is converted to hydrophilic nature, in contrast to the SFCP 1. Moreover, in this study, we also report a selective gas adsorption study of two C2 gases with similar kinetic diameters (∼3.9 Å) of ethylene over ethane.
Variance estimation after imputation is an important practical problem in survey sampling. When deterministic imputation or stochastic imputation is used, we show that the variance of the imputed ...estimator can be consistently estimated by a unifying linearize and reverse approach. We provide some applications of the approach to regression imputation, fractional categorical imputation, multiple imputation and composite imputation. Results from a simulation study, under a factorial structure for the sampling, response and imputation mechanisms, show that the proposed linearization variance estimator performs well in terms of relative bias, assuming a missing at random response mechanism.
Area‐level unmatched sampling and linking models have been widely used as a model‐based method for producing reliable estimates of small‐area means. However, one practical difficulty is the ...specification of a link function. In this paper, we relax the assumption of a known link function by not specifying its form and estimating it from the data. A penalized‐spline method is adopted for estimating the link function, and a hierarchical Bayes method of estimating area means is developed using a Markov chain Monte Carlo method for posterior computations. Results of simulation studies comparing the proposed method with a conventional approach based on a known link function are presented. In addition, the proposed method is applied to data from the Survey of Family Income and Expenditure in Japan and poverty rates in Spanish provinces.
Classroom assessment is the process of documenting the knowledge, skills, attitudes and beliefs of learners. It provides essential feedback to both instructors and students to improve their teaching ...methods for guiding and motivating students to be actively involved in their learning. Assessment drives learning. Formative assessments enable the instructor to guide the students to learn well. Summative assessments enable the measurement of levels of attainment of course outcomes and act as feedback to course design and curriculum improvement. This article presents the underlying principles of assessment through a discussion of assessment approaches and their purposes, types of assessment items, quality of assessment and summative assessment plans. Quality assessment instruments can be developed through an understanding of the quality attributes of assessment items, the process of designing assessment instruments, designing a variety of assessment items, and devising plans to evaluate them through rubrics. An approach is presented for creating a summative assessment plan that can also lead to the attainment of outcomes as per the requirements of programme accreditation.
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