Periodic integer-valued GARCH(1, 1) model

This article deals with some probabilistic and statistical properties of a periodic integer-valued GARCH(1,1) model. Necessary and sufficient conditions for the periodical stationary, both in mean and second order, are established. The closed-forms of the mean and the second moment are, under these conditions, obtained. The condition of the existence of higher moment orders and their explicit formula in terms of the parameters are established. The autocovariance structure is studied, while providing the closed-form of the periodic autocorrelation function. The Yule–Walker and the likelihood estimations of the underlying parameters are obtained. A simulation study and an application on real dataset are provided.     

An On-Line Estimation Algorithm for Periodic Autoregressive Models

This paper develops an on-line estimation algorithm for periodic autoregressive models (PAR). Indeed, we provide an adaptation of the well known recursive least squares algorithm (RLS), which has been successfully applied to classical autoregressive models (AR), to deal with PAR models. The obtained estimators are shown to be asymptotically efficient under mild conditions. Moreover, the performance of the periodic least squares algorithm (PRLS) is assessed via an intensive simulation study.     

Post-Political Transitions in Arab Spring Countries: The Challenges

This paper aims at examining the impact of political transitions on democracy, corruption and growth in countries which knew democratic changes. The results of our study indicate that these changes positively affect implementation of democratic principles, the struggle against corruption and economic growth. We examined also the case of the Arab spring countries focusing on the main political and socio-economic challenges and most importantly the religious challenge which is a characteristic of these countries. Indeed, religion may be considered as a relevant variable in these transitions and consequently it is very difficult to claim short-term or long-term triumph of these transitions as Arabs are now in a political boiling phase where religion may gather unexpected results.     

Adjusting for covariates in non-inferiority studies with margins defined as risk differences

Adjusting for covariates makes efficient use of data and can improve the precision of study results or even reduce sample sizes. There is no easy way to adjust for covariates in a non-inferiority study for which the margin is defined as a risk difference. Adjustment is straightforward on the logit scale, but reviews of clinical studies suggest that the analysis is more often conducted on the more interpretable risk-difference scale. We examined four methods that allow for adjustment on the risk-difference scale: stratified analysis with Cochran-Mantel-Haenszel (CMH) weights, binomial regression with an identity link, the use of a Taylor approximation to convert results from the logit to the risk-difference scale and converting the risk-difference margin to the odds-ratio scale. These methods were compared using simulated data based on trials in HIV. We found that the CMH had the best trade-off between increased efficiency in the presence of predictive covariates and problems in analysis at extreme response rates. These results were shared with regulatory agencies in Europe and the USA, and the advice received is described.     

Household and Contextual Indicators of Poverty in Tunisia: A Multilevel Analysis

Using micro data from the 2010 National Survey on Households’ Budget, Consumption and Standard of Living, this study aims to investigate main factors contributing to poverty distribution, one of the most severe socioeconomic problems in Tunisia. To this end, we use a multilevel Logit model and a multilevel mixed linear model to simultaneously analyze the micro-level (household) and macro-level (governorate) factors that might affect the household poverty status. Household size, household composition, occupation, education levels, the gender of the household head and the number of earner by household variables were assessed at the micro-level. Unemployment rate, poverty rate, industrial and agriculture parts and the migration are included to control the effect of contextual effects. Our findings showed that the likelihood of household being poor is positively and significantly related to household size, more children and lower education level. Extreme poverty is more likely to occur in rural than urban areas. Macro-level analyses indicated that greater neighbourhood unemployment rate was associated with higher odds of poverty, while greater industrial agglomeration and migration balance were associated with reduced odds of poverty.     

Screening for recommended antenatal risk factors: How long does it take?

Background

Detection and management of antenatal risk factors is critical for quality care.

Sexual Dysfunction among Male Patients with Tramadol abuse: A Case-Control Study

Objective: Here we have investigated the association between tramadol abuse and male sexual function. Methods: Eighty-two male tramadol abuse patients and 55 healthy controls (20- to 45-years-old) were included in the study. Data from a sociodemographic questionnaire and the International Index of Erectile Function Questionnaire were collected and analyzed. Results: The tramadol abuse patients were 5 times more likely than their healthy counterparts to have erectile dysfunction. The tramadol abuse patients also had worse scores in the orgasmic, sexual desire, intercourse satisfaction, and overall satisfaction domains compared to the controls. Conclusion: Sexual dysfunctions are common among tramadol abuse patients.     

“You Always Remain Slightly an Outsider”: Workplace Experiences of Academics from Working‐Class or Impoverished Backgrounds

Debates surrounding class inequality and social mobility often highlight the role of higher education in reducing income inequality and promoting equity through upward social mobility. We explore the lived experience of social mobility through an analysis of 11 semistructured interviews with Canadian academics who self‐identified as having working‐class or impoverished family origins. While economic capital increased substantially, cultural capital and habitus left many feeling like cultural outsiders. Isolation—both chosen and imposed—reduced professional networks, diminishing social capital. Caught between social worlds, participants mobilized symbolic capital in moral boundary marking, aligning themselves strategically with either their current class status or their working‐class roots. While upward social mobility is a path toward reducing economic inequality, the lived experience of social mobility suggests it may exact a high emotional cost.