Départ Des Enfants Et Contraction Des Familles D'Après Les Recensements Canadiens De 1971 Et De 1981

Censuses do not usually collect information on the departure of children and the consequent contraction of the family; however, they sometimes do include useful information on these phenomena and their evolution. On these questions this article presents a new use of the 1971 and 1981 Canadian censuses. From the analysis, it is estimated that the timing of children's departure from their family of origin was almost the same in 1981 as in 1971; median age at departure was identical: 20.5 for women and 22.3 for men. Broken families, more numerous than in the past, become contracted earlier than unbroken families; among unbroken families, the contraction phase started earlier in 1981 than in 1971 among large or medium-sized families while it began later among small families. The method developed here succeeds with the Canadian data in palliating the lack of surveys; it would be interesting to test it on data from other Western societies.     

Energy cost saving starts on the shop floor

This paper describes how one company, the British subsidiary of an American multinational, met the problem of continually rising energy costs with a carefully co-ordinated energy conservation programme. This was linked with a pollution prevention programme and the environment and energy used an equation for cutting costs.     

Work-related factors contributing to chronic disability in low back pain

Low back pain is a costly and incapacitating musculoskeletal disorder. Prospective studies documenting the capacity of work-related factors to predict chronicity are few in number, the methodology used is very diversified, and the results obtained diverge. The aim of the present study is to investigate the capacity of work-related objective (non-psychosocial) and psychosocial factors to predict chronic disability related to low back pain. A longitudinal prospective study with two measurement times was carried out. The sample (N = 258) consisted of workers with subacute low back pain who were on sick leave and receiving compensation from the CSST (Quebec Workers' Compensation Board). Of all the work-related variables measured, perceived stress and fears and beliefs about work were associated with return to work status at the six-month follow-up. The results obtained show the importance of considering fears and beliefs about work when identifying people in the subacute phase of low back pain who are at risk of developing chronic disability.     

Free Knot Splines with RJMCMC in Survival Data Analysis

The B-spline representation is a common tool to improve the fitting of smooth nonlinear functions, it offers a fitting as a piecewise polynomial. The regions that define the pieces are separated by a sequence of knots. The main difficulty in this type of modeling is the choice of the number and the locations of these knots. The Reversible Jump Markov Chain Monte Carlo (RJMCMC) algorithm provides a solution to simultaneously select these two parameters by considering the knots as free parameters. This algorithm belongs to the MCMC techniques that allow simulations from target distributions on spaces of varying dimension. The aim of the present investigation is to use this algorithm in the framework of the analysis of survival time, for the Cox model in particular. In fact, the relation between the hazard ratio function and the covariates being assumed to be log-linear, this assumption is too restrictive. Thus, we propose to use the RJMCMC algorithm to model the log hazard ratio function by a B-spline representation with an unknown number of knots at unknown locations. This method is illustrated with two real data sets: the Stanford heart transplant data and lung cancer survival data. Another application of the RJMCMC is selecting the significant covariates, and a simulation study is performed.