Optimal Method for Realizing Two-Sided Inferences About a Linear Combination of Two Proportions

In order to reach the inference about a linear combination of two independent binomial proportions, various procedures exist (Wald's classic method, the exact, approximate, or maximized score methods, and the Newcombe-Zou method). This article defines and evaluates 25 different methods of inference, and selects the ones with the best behavior. In general terms, the optimal method is the classic Wald method applied to the data to which z ² _α/2/4 successes and z ² _α/2/4 failures are added (≈1 if α = 5%) if no sample proportion has a value of 0 or 1 (otherwise the added increase may be different).

Supplemental materials are available for this article. Go to the publisher's online edition of Communications in Statistics - Simulation and Computation to view the free supplemental file.     

Effects of age and physical activity on response speed in knee flexor and extensor muscles

This study aims to determine the normalized response speed (V _rn) in vastus lateralis (VL) and biceps femoris (BF) muscles in different age groups using tensiomyography. Eighty-four male subjects were divided into four age groups: teenage subjects (T); undergraduate students (U), adult subjects (A), and the elderly group (E). Differences in V _rn were observed between E and T (p?=?0.000), E and U (p?=?0.000), and E and A (p?=?0.018) for right VL and between E and T (p?<?0.000) and U (p?=?0.003) for left VL; between T and U (p?=?0.010) and A (p?=?0.000) for right VL, and A (p?=?0.004) for left VL. V _rn in the BF displayed different behavior from that of the VL, increasing moderately or stabilizing and declining slightly in E, in right leg (p?=?0.020). The data obtained highlighted a decline in V _rn for the VL in both legs with increasing age and, declines in BF response speed were observed only in E.     

Why is not design of experiments widely used by engineers in Europe?

An extensive literature review was carried out to detect why design of experiments (DoE) is not widely used among engineers in Europe. Once 16 main barriers were identified, a survey was carried out to obtain first-hand information about the significance of each. We obtained 101 responses from academics, consultants and practitioners interested in DoE. A statistical analysis of the survey is introduced, including: (a) a ranking of the barriers, (b) grouping of barriers using factorial analysis, (c) differences between characteristics of respondents. This exploratory analysis showed that the main barriers that hinder the widespread use of DoE are low managerial commitment and engineers’ general weakness in statistics. Once the barriers were classified, the most important resultant group was that related to business barriers.     

Technological change and employment in Brazil,Colombia and Mexico: Which workers are most affected?

This article adopts a task-based approach to analyse employment patterns in terms of skill distribution and occupations in the urban labour markets of Brazil, Colombia and Mexico during 2002–15. The results suggest that employment fell strongly for some medium-skilled occupations, and increased slightly for both low-skilled and high-skilled occupations. Decomposition results suggest that the decreasing share of employment of secretaries and stenographers is fully explained by changes within industries (routinization hypothesis), whereas the decrease in machinery operation and handicraft jobs is mainly explained by changes between industries. By socio-demographic group, technological changes negatively affected women but benefited younger workers and those with higher educational attainment.     

DIFFERENCES IN CITATION PATTERNS ACROSS JOURNAL TIERS: THE CASE OF ECONOMICS

We study how citation patterns differ between journal tiers in economics by analyzing citations patterns of more than 6,000 research articles published in top five, second tier, and top field economics journals. We find that top five journals' articles receive more citations and that the life cycles of those citations are longer. However, their influence (in term of citations) is overestimated: in its first twenty years since publication, the median top five article accumulates 4.25 as many citations when compared to non-top five median articles. This ratio is strongly associated with the field of economics research and with articles' impact. (JEL A14)     

The effects of wage flexibility on activity and employment in Spain

In this paper we estimate the macroeconomic effects of the greater wage and firms’ internal flexibility promoted by the economic policies implemented since 2012, which changed markedly Spanish labour regulations. To do so, we propose a structural VAR that allows us to break down changes in main macroeconomic variables into different structural shocks. From a policy perspective, the estimation of the structural shocks allows us to simulate a counterfactual scenario, whereby we conclude that the effects of less rigid labour market are positive and significant. Our results suggest that, if these policies were implemented at the beginning of the crisis, they could have avoided a significant part of the falls in GDP and employment.     

Imputation of repeatedly observed multinomial variables in longitudinal surveys

It is now a standard practice to replace missing data in longitudinal surveys with imputed values, but there is still much uncertainty about the best approach to adopt. Using data from a real survey, we compared different strategies combining multiple imputation and the chained equations method, the two main objectives being (1) to explore the impact of the explanatory variables in the chained regression equations and (2) to study the effect of imputation on causality between successive waves of the survey. Results were very stable from one simulation to another, and no systematic bias did appear. The critical points of the method lied in the proper choice of covariates and in the respect of the temporal relation between variables.     

Bootstrap Prediction Intervals for Factor Models

We propose bootstrap prediction intervals for an observation h periods into the future and its conditional mean. We assume that these forecasts are made using a set of factors extracted from a large panel of variables. Because we treat these factors as latent, our forecasts depend both on estimated factors and estimated regression coefficients. Under regularity conditions, asymptotic intervals have been shown to be valid under Gaussianity of the innovations. The bootstrap allows us to relax this assumption and to construct valid prediction intervals under more general conditions. Moreover, even under Gaussianity, the bootstrap leads to more accurate intervals in cases where the cross-sectional dimension is relatively small as it reduces the bias of the ordinary least-squares (OLS) estimator.     

Social innovation indicators

This article provides the results of the Regional Social Innovation Index (RESINDEX), a conceptual and empirical model that explores indicators of social innovation at organizational and regional level. The RESINDEX model links absorptive capacity of knowledge and social innovation in four types of key regional agents: profit and non-profit organizations, universities, and technological centres. The pilot application of the RESINDEX model held in the Basque Country (Spain) during the year 2013. Within the framework of this study 282 regional organizations were surveyed. The article contributes to the conceptual and empirical discussion on indicators in social innovation.     

Quasi-likelihood ratio tests for cointegration,cobreaking, and cotrending

We consider a set of variables with two types of nonstationary features, stochastic trends and broken linear trends. We develop tests that can determine whether there is a linear combination of these variables under which the nonstationary features can be canceled out. The first test can determine whether stochastic trends can be eliminated and thus whether cointegration holds, regardless of whether structural breaks in linear trends are eliminated. The second test can determine whether both stochastic trends and breaks in linear trends are simultaneously removed and thus whether cointegration and cobreaking simultaneously hold. The third test can determine whether not only breaks in linear trends but also linear trends themselves are eliminated along with stochastic trends and thus whether both cointegration and cotrending hold.