Inference on Categorical Survey Response: A Predictive Approach

We consider the estimation of finite population proportions of categorical survey responses obtained by probability sampling. The customary design-based estimator does not make use of the auxiliary data available for all the population units at the estimation stage. We adopt a model-based predictive approach to incorporate this information and make the estimates more efficient. In the first part of our paper we consider a multinomial logit type model when logit function is a known parametric function of the covariates. We then use it for the prediction of non-sampled responses. This together with sampled responses is used to obtain the estimates of the proportions. The asymptotic biases and variances of these estimators are obtained. The main drawback of this approach is, being a parametric model it may suffer from model misspecification and thus, may lose it’s efficiencies over the usual design-based estimates. To overcome this drawback, in the next part of this paper we replace the multinomial logit type model by a nonparametric model using recently developed random coefficients splines models. Finally, we carry out a simulation study. It shows that the nonparametric approach may lead to an appreciable improvement over both parametric and design-based approaches when the regression function is quite different from multinomial logit.

Hunting extra dimensions in the shadow of Sgr A*

We show that the observed angular diameter of the shadow of the ultra compact object Sgr A*, favours the existence of an extra spatial dimension. This holds irrespective of the nature of the ultra compact object, i.e., whether it is a wormhole or, a black hole mimicker, but with the common feature that both of them have an extra dimensional origin. This result holds true for the mass and the distance measurements of Sgr A* using both Keck and the Gravity collaborations and whether we use the observed image or, the observed shadow diameter. In particular, the central value of the observed shadow or, the observed image diameter predicts non-zero hairs inherited from the extra dimensions.Comment: v1, 18 pages, 4 figure

Prevalence and determinants of geriatric malnutrition among rural populations: A Community based cross-sectional Study in Eastern India

Background: The World’s population is aging due to simultaneous declining of birth as well as death rate leading to the phenomenon of demographic burden. The dependent population compounded by their chronic morbidities have little resources left to maintain a healthy nutrition, culminating in another morbidity i.e., geriatric malnutrition, which is grossly un-diagnosed and un-reported. A commitment to the Sustainable Development Goals means a commitment to Healthy Ageing, hence WHO had declared the next decade (2020-2030) as the “Decade on Healthy Ageing”.  Thereby, the present study aims to find the prevalence and correlates of elderly malnutrition in the index population. Methodology: A cross-sectional study was conducted among 180 geriatric individuals of Bankura district of West Bengal using 30 cluster sampling design. Data on nutritional status were collected using MNA-SF questionnaire and correlates were assessed by a pre-designed pre-tested schedule Multivariable logistic regression was done to ascertain the factors influencing elderly malnutrition. Results: Prevalence of geriatric malnutrition was 32.2% and risk of malnutrition was 48.89%. Presence of chronic diseases, poor socio-economic status, polypharmacy, food insecurity, catastrophic health expenditure and absence of social insurance were found to be significantly associated with geriatric malnutrition Conclusion: Geriatric malnutrition was found to be considerably high in the study population. The complex interplay of multiple factors was found to culminate it, upon which socio-economic and health care affordability issues were prominent. A multi-disciplinary approach focusing on social security, improved health care delivery with Patient Oriented Evidence that Matters (POEM) approach may help in mitigating the issue