Permuting incomplete paired data: a novel exact and asymptotic correct randomization test

Various statistical tests have been developed for testing the equality of means in matched pairs with missing values. However, most existing methods are commonly based on certain distributional assumptions such as normality, 0-symmetry or homoscedasticity of the data. The aim of this paper is to develop a statistical test that is robust against deviations from such assumptions and also leads to valid inference in case of heteroscedasticity or skewed distributions. This is achieved by applying a clever randomization approach to handle missing data. The resulting test procedure is not only shown to be asymptotically correct but is also finitely exact if the distribution of the data is invariant with respect to the considered randomization group. Its small sample performance is further studied in an extensive simulation study and compared to existing methods. Finally, an illustrative data example is analysed.     

Estimation of P{X < Y} for geometric—exponential model based on complete and censored samples

This article deals with the estimation of R = P{X < Y}, where X and Y are independent random variables from geometric and exponential distribution, respectively. For complete samples, the MLE of R, its asymptotic distribution, and confidence interval based on it are obtained. The procedure for deriving bootstrap-p confidence interval is presented. The UMVUE of R and UMVUE of its variance are derived. The Bayes estimator of R is investigated and its Lindley's approximation is obtained. A simulation study is performed in order to compare these estimators. Finally, all point estimators for right censored sample from the exponential distribution, are obtained.     

Minimum variance unbiased estimation of stress–strength reliability under bivariate normal and its comparisons

In many industrial and natural phenomena, we need the probability that a component is smaller than the other component. Under a stress–strength model, this is reliability of an item. Under independent setup, there are different approaches for the estimation of such reliability. Here, estimation is considered under the dependent case. Under bi-variate setup uniformly minimum variance unbiased estimator is obtained. Also comparison with available estimator based on Maximum Likelihood Estimate (MLE) is done through Mean Square Error (MSE) and bias. Also these are compared by computing L₁ distance between their distribution functions. From this idea and numerical computations, UMVUE appears to be good.     

On some aspects of a generalized alternative zero-inflated logarithmic series distribution

Here, we consider a generalized form of the alternative zero-inflated logarithmic series distribution of Kumar and Riyaz (J. Statist. Comp. Simul., 2015) and study some of its important aspects. The parameters of the distribution are estimated by the method of maximum likelihood and some test procedures are developed for testing the significance of the additional parameter of the model. All these estimation and testing procedures are illustrated with the help of certain real life datasets. A simulation study is also carried out for assessing the performance of the estimators.     

On the performance of Turing's formula: A simulation study

Turing's formula is an amazing result that allows one to estimate the probability of observing something that has not been observed before. After a brief review of the literature, we perform a simulation study to better understand how well this formula works in a variety of situations. We also compare the performance of Turing's formula with several modifications that have appeared in the literature. We find that these modifications tend to outperform Turing's formula, but usually not by very much. We further find that Turing's formula and its modifications tend to work better for heavy-tailed distributions than for light-tailed ones.     

The discrepancy of P-values and posterior probability: Two-sided hypothesis of variance of normal distribution with unknown mean

This article is concerned with the comparison of P-value and Bayesian measure in point null hypothesis for the variance of Normal distribution with unknown mean. First, using fixed prior for test parameter, the posterior probability is obtained and compared with the P-value when an appropriate prior is used for the mean parameter. In the second, lower bounds of the posterior probability of H₀ under a reasonable class of prior are compared with the P-value. It has been shown that even in the presence of nuisance parameters, these two approaches can lead to different results in the statistical inference.     

Visibly ageing femininities: women’s visual discourses of being over-40 and over-50 on Instagram

Abstract

This article explores visual discourses about over-40 and over-50 femininities that emerge from women’s own Instagram accounts. It analyses women’s visual and textual rhetoric of what over-40 and over-50 looks like, and whether it could interrupt the ageist, sexist, and body-normative discourses of female ageing and visibility. Intertextual visual discourse analysis of images, captions, and hashtags reveals two dominant themes (fitness and fashion) and two repeating rhetorical elements (motherhood and self-sufficiency) through which women make themselves visible as over-40/50. A few explicitly subversive discourses (i.e., over-40 fatshion account) exist, but a discourse of a healthy, fit, fashionable, independent, self-sufficient, and happy mother over-40/50 is prevalent. It easily lends itself to being interpreted as an insidious reproduction of post-feminist ideology, but I argue that there are moments of critique and subversion within. Thus, a reparative reading that acknowledges moments of disconnect from the discourse that normalizes ageing women’s limited or non-existent visibility is offered.     

Fetal movements: What are we telling women?

Problem

Information that women receive about the importance of monitoring fetal movements and what to do if there are changes is inconsistent and may not be evidence based.

Examples of practice: an intercultural approach to translate Romanian children’s folklore into Spanish

Due to the great number of Romanian pupils in Spanish public school, the local administration organises extra-curricular Romanian courses in order to preserve the Romanian language and culture. This is a way to contribute to build and consolidate a bicultural and bilingual profile of the young people. Besides, it is also an opportunity to align with plurilingual and pluricultural competence established by The Common European Framework of References for Languages (2002). Based on the premise that “children's literature is an intercultural instrument”, I choose as corpus the Romanian children's folklore represented by games, formula-songs, recital-stories, household words, incantations, riddles and lullabies to translate into Spanish. After the translations, Romanian children had to find similarities and differences between the Romanian and Spanish children's songs, in order to augment the knowledge about both cultures.