Correlated random effects regression analysis for a log-normally distributed variable

In regression analysis, it is assumed that the response (or dependent variable) distribution is Normal, and errors are homoscedastic and uncorrelated. However, in practice, these assumptions are rarely satisfied by a real data set. To stabilize the heteroscedastic response variance, generally, log-transformation is suggested. Consequently, the response variable distribution approaches nearer to the Normal distribution. As a result, the model fit of the data is improved. Practically, a proper (seems to be suitable) transformation may not always stabilize the variance, and the response distribution may not reduce to Normal distribution. The present article assumes that the response distribution is log-normal with compound autocorrelated errors. Under these situations, estimation and testing of hypotheses regarding regression parameters have been derived. From a set of reduced data, we have derived the best linear unbiased estimators of all the regression coefficients, except the intercept which is often unimportant in practice. Unknown correlation parameters have been estimated. In this connection, we have derived a test rule for testing any set of linear hypotheses of the unknown regression coefficients. In addition, we have developed the confidence ellipsoids of a set of estimable functions of regression coefficients. For the fitted regression equation, an index of fit has been proposed. A simulated study illustrates the results derived in this report.     

Sparrows in urban complexity: macro and micro-scale habitat use of sympatric sparrows in Guwahati City,India

In recent decades the House Sparrow and Tree Sparrow have suffered considerable declines. To date, little is known about the fine scale habitat selection of sparrows where they occur together. We investigated how sympatric sparrows used macro and microhabitats in the urban environment of Guwahati city. Survey of sparrows was carried out in 572 locations of different urban settings to find out the city scale distribution. We classified urban habitats and collected micro-habitat variables at 45 point count stations during 2013–2015. Urbanization gradient was found to be influential in limiting the abundance of sparrows. House Sparrow was more common within the urbanized areas compared to low settlement densities located far from the urban core. In contrast, Tree Sparrows were more scattered and seldom found in crowded areas. Spatial overlap was comparatively high in the residential areas adjacent to hillocks. At micro scale, House Sparrow had quadratic response to the degree of urbanization. Both the species avoided areas where urbanization reached the peak; specifically, the areas which were completely devoid of natural vegetation and top soil was paved, and in shopping centers with glass facades. Habitat requirements of both the species at local landscape scale seemed to be similar, although, with some overlaps, they occupied different gradients of the urban environment. Since urban landscapes are highly managed, the fundamental tool for enhancing urban sparrow populations would be the protection of mosaic habitat prioritizing suitable design and management of private gardens and allotments.

     

A Variable Selection Criterion in the Linear Programming Approaches to Discriminant Analysis*

There are numerous variable selection rules in classical discriminant analysis. These rules enable a researcher to distinguish significant variables from nonsignificant ones and thus provide a parsimonious classification model based solely on significant variables. Prominent among such rules are the forward and backward stepwise variable selection criteria employed in statistical software packages such as Statistical Package for the Social Sciences and BMDP Statistical Software. No such criterion currently exists for linear programming (LP) approaches to discriminant analysis. In this paper, a criterion is developed to distinguish significant from nonsignificant variables for use in LP models. This criterion is based on the “jackknife” methodology. Examples are presented to illustrate implementation of the proposed criterion.     

Social Support and its Correlation with Loneliness and Subjective Well-being: A Cross-cultural Study of Older Nepalese Adults

Population aging in Nepal is a recent phenomenon, due more to demographic changes than to socio-economic development. The study had three goals: to analyze the social support exchange among elderly men and women; to discover the main sources of support in loneliness and subjective well-being in the elderly; and to study the cross-cultural differences in support among elderly Chhetri ( N  = 137, mean age = 69.1 [7.2] years) and Newar people ( N  = 195, mean age = 68.8 [7.7] years) in one ward in Kathmandu. The data were collected using face-to-face interviews. The dependent variables were loneliness and subjective well-being (SWB). The results for both ethnic Chhetri and Newar respondents show that their major support comes from their children living in the same household and their spouses. I conclude that the sources of social support and social support exchange are similar between the two castes/ethnicities and that there are no cross-cultural differences between them in terms of support for loneliness and SWB-life stability, although there are cross-cultural differences in their SWB-life satisfaction. Providing social support to friends and neighbors appears to be related to less loneliness and increased SWB in both castes/ethnicities.     

Progressively censored tests for clinical experiments and life testing problems based on weighted empirical distributions

In the context of time-sequential studies, progressively censored tests for a simple regression model based on weighted empirical distributions are considered for ungrouped as well as grouped data situations. Early decision rules based on such tests are formulated. The asymptotic theory of the proposed tests rests on a construction of suitable empirical processes and their convergence (in distribution) to appropriate Gaussian functions. Critical values of the proposed test statistics are obtained by simulation, For a hypothetical example (of practical interest), a comparative study is made for the empirical powers and stopping times for some rival tests.     

A one-sided test for testino homogeneity of scale parameters against simple ordered alternative

In an earlier paper the authors (1997) extended the results of Hayter (1990) to the two parameter exponential probability model. This paper addressee the extention to the scale parameter case under location-scale probability model. Consider k (k≧3) treatments or competing firms such that an observation from with treatment or firm follows a distribution with cumulative distribution function (cdf) F_i(x)=F[(x-μ_i)/Q_i], where F(·) is any absolutely continuous cdf, i=1,…,k. We propose a test to test the null hypothesis H₀:θ₁=…=θ_k against the simple ordered alternative H₁:θ₁≦…≦θ_k, with at least one strict inequality, using the data X_i,j, i=1,…k; j=1,…,n₁. Two methods to compute the critical points of the proposed test have been demonstrated by talking k two parameter exponential distributions. The test procedure also allows us to construct simultaneous one sided confidence intervals (SOCIs) for the ordered pairwise ratios θ_j/θ_i, 1≦i<j≦k. Statistical simulation revealed that: 9i) actual sizes of the critical points are almost conservative and (ii) power of the proposed test relative to some existing tests is higher.     

Civic-secular and ethnic nationalisms as bases of the nation-state: multiculturalism at the crossroads? 1

The dominant Eurocentric paradigm of the nation and the nation-state was premised on western historical experience that was indigenous to the west but claimed universality for the rest. Many post-colonial countries, particularly those that went through national liberation struggles, like India and China, with multi-ethnic mobilisations, established sovereign states. The nationalist leaders claimed the unity of nationhood for their culturally diverse countries (states), with their millennia-deep civilisational identity, compelling a new discourse on the untenability of the classic Eurocentric paradigm. The second development witnessed the inevitable cultural heterogenisation of the western countries premised on the expansion of the (immigrant) labour market through an ever-enveloping regime of economic liberalisation and world trade. The catharsis of the invasion of cheaper labour from culturally diverse countries, often native-displacing, resulted in western countries attempting to accommodate the emerging changing reality in the context of mono-cultural nations through the concept and policy of multiculturalism. In spite of this, western countries have been witness to intercultural violence, racial discrimination and threats of home grown terrorism. The paper seeks to distinguish between ‘pluralism’ and ‘multiculturalism’ and argues for a reformulation of the concept of the nation-state that will have greater applicability across states.     

Child Rights Practice among the Indigenous Communities in Bangladesh

The objective of this article was to explore the practice of child rights among the indigenous communities of Bangladesh. We used a mixed method approach to collect data from four ethnic communities in the Bandarban District of the Chittagong Division in Bangladesh. We questioned children, parents, community members, local leaders, and service providers of those communities on a number of child rights issues, for example, child education, child labor, child recreation and culture, parents' guidance to children for capacity development, and access to child rights at home and in the community according to Convention on the Rights of the Child treaty. The results showed that while the community was aware of child rights, financial vulnerability and a lack of social support meant that these rights could not be upheld in practice. The paper urges improvement of social support, including income generation activities for indigenous communities.     

Some imputation methods to compensate with non-response for estimation of population mean in two-occasion successive sampling

Abstract

Non-response is an unavoidable phenomenon in almost all sample survey, and if it is not dealt carefully at the very starting of the analysis, results may lead to significant biases in the survey estimates. Keeping these facts in mind and inspired by the work of Singh (2009 Singh, S. 2009. A new method of imputation in survey sampling. Statistics 43 (5):499–511. doi:10.1080/02331880802605114.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]), this article suggests some alternative efficient methods to deal with the missing data problems at the beginning of the analysis and proposes estimation procedures of the current population mean in two-occasion successive sampling. The properties of the resultant estimation procedures have been examined and supplemented with empirical studies. Results have been critically analyzed, and recommendations are made to the survey practitioners.     

Mutiple three-decision procedure for comparing several exponential treatments with the best control

In this paper, the three-decision procedures to classify p treatments as better than or worse than one control, proposed for normal/symmetric probability models [Bohrer, Multiple three-decision rules for parametric signs. J. Amer. Statist. Assoc. 74 (1979), pp. 432–437; Bohrer et al., Multiple three-decision rules for factorial simple effects: Bonferroni wins again!, J. Amer. Statist. Assoc. 76 (1981), pp. 119–124; Liu, A multiple three-decision procedure for comparing several treatments with a control, Austral. J. Statist. 39 (1997), pp. 79–92 and Singh and Mishra, Classifying logistic populations using sample medians, J. Statist. Plann. Inference 137 (2007), pp. 1647–1657]; in the literature, have been extended to asymmetric two-parameter exponential probability models to classify p(p≥1) treatments as better than or worse than the best of q(q≥1) control treatments in terms of location parameters. Critical constants required for the implementation of the proposed procedure are tabulated for some pre-specified values of probability of no misclassification. Power function of the proposed procedure is also defined and a common sample size necessary to guarantee various pre-specified power levels are tabulated. Optimal allocation scheme is also discussed. Finally, the implementation of the proposed methodology is demonstrated through numerical example.