Effects of international student exchange on pre-service teachers: a quasi-experimental study

This contribution provides empirical answers to the question of how teaching-specific competencies develop during participation in an international student exchange programme. The quantitative analyses of this quasi-experimental study suggest that, generally speaking, no specific developments occur during an exchange experience. These findings contradict the majority of existing literature. Possible reasons for this divergence are discussed. The interpretation of the results suggests future research should focus on the key question of pre-conditions for productive exchange experiences.     

On testing for independence between the innovations of several time series

Test statistics for checking the independence between the innovations of several time series are developed. The time series models considered allow for general specifications for the conditional mean and variance functions that could depend on common explanatory variables. In testing for independence between more than two time series, checking pairwise independence does not lead to consistent procedures. Thus a finite family of empirical processes relying on multivariate lagged residuals are constructed, and we derive their asymptotic distributions. In order to obtain simple asymptotic covariance structures, Möbius transformations of the empirical processes are studied, and simplifications occur. Under the null hypothesis of independence, we show that these transformed processes are asymptotically Gaussian, independent, and with tractable covariance functions not depending on the estimated parameters. Various procedures are discussed, including Cramér–von Mises test statistics and tests based on non‐parametric measures. The ranks of the residuals are considered in the new methods, giving test statistics which are asymptotically margin‐free. Generalized cross‐correlations are introduced, extending the concept of cross‐correlation to an arbitrary number of time series; portmanteau procedures based on them are discussed. In order to detect the dependence visually, graphical devices are proposed. Simulations are conducted to explore the finite sample properties of the methodology, which is found to be powerful against various types of alternatives when the independence is tested between two and three time series. An application is considered, using the daily log‐returns of Apple, Intel and Hewlett‐Packard traded on the Nasdaq financial market. The Canadian Journal of Statistics 40: 447–479; 2012 © 2012 Statistical Society of Canada     

The Effect of Grandparental Support on Mothers’ Labour Market Participation: An Instrumental Variable Approach

Childcare arrangements are key in women’s ability to juggle motherhood and work outside the home. As such, the study of access to childcare and its use is of great policy relevance. We focus on a particular kind of informal childcare, the one provided by grandparents. Empirically, assessing the effect of grandparental childcare is not an easy task due to unobserved preferences. In light of the potential outcome framework, we interpret the biases resulting from unobserved preferences as arising from the non-compliance of mothers to the availability of grandparents and from preferences of grandparents for activities other than childcare. Using an instrumental variable approach on Italian data, we find that the effect of grandparental childcare on mothers’ labour supply is positive, statistically significant and economically relevant. The effect is stronger for less educated mothers, with young children and living in northern and central Italy.     

Use of the scale-up methods in injury prevention research: An empirical assessment to the case of choking in children

The scale-up method estimates the size of hard to count subpopulations. This method is based on the idea that the proportion of subjects in a subpopulation E known to each member of the general population T is the same as the proportion of members of E belonging to general population T.