A Non-parametric Frailty Model for Temporally Clustered Multivariate Failure Times

Abstract A model is introduced here for multivariate failure time data arising from heterogenous populations. In particular, we consider a situation in which the failure times of individual subjects are often temporally clustered, so that many failures occur during a relatively short age interval. The clustering is modelled by assuming that the subjects can be divided into ‘internally homogenous’ latent classes, each such class being then described by a time‐dependent frailty profile function. As an example, we reanalysed the dental caries data presented earlier in Härkänen et al. [Scand. J. Statist. 27 (2000) 577], as it turned out that our earlier model could not adequately describe the observed clustering.     

What influences the size of child maintenance payments? A register‐based study of maintenance payments in Finland

The aim of this study was to explore how particular economic and demographic factors contribute to the level of the child maintenance payment (CMP) paid by the non‐resident parent. For this study, we used 5‐year longitudinal panel data from years 2009 to 2013 consisting of over 80,000 non‐resident parents from the Finnish Tax Administration and The Finnish Population Register Centre. Results from regression models indicate that the single biggest factor affecting the size of CMPs is the number of dependent children. We found that the non‐resident parent's higher income is associated with higher CMPs and that non‐resident fathers pay on average larger CMPs than non‐resident mothers, even after accounting for differences in income. Unexpectedly, we found that the age of the dependent child did not predict changes in CMPs. This suggests that once formal CMP‐contracts are determined between the parents, they are seldom changed. Our results suggest that some degree of mandatory periodic review for maintenance contracts is worth considering.     

Stochastic complexity and the mdl principle

A Search for the stochastic complexity of the observed data, as the greates lower bound with which the data can be encoded, represents a global maximum likelihood principle, which permits comparison of models regardless of the number of parameters in them. For important special classes, such as the guassian and the multinomial models, formulas for the stochastic complexity give new and powerful model selection criteria,while in the general case approximations can be computed with the MDL principle. Once a model is found with which the stochastic complexity is reached, there is nothing further to learn from the data with the proposed models. The basic notions are reviewed and numerical examples are given.     

The state and future of social service enterprises—a Finnish case

There has been a rapid increase in private social services in Finland, where the tradition of social care services has placed the main emphasis on public services. The aim of this article is to compare the situation of Finnish social service enterprises in 2001 and 2005/2006, in the light of two national surveys, in order to increase knowledge about the state and the future of such enterprises as providers of social care. Particular attention is paid to the profiles of men and women as entrepreneurs, as these differed somewhat. The composition of private care enterprises and their management remained fairly similar between 2001 and 2005/2006. Most of the enterprises were owned by middle-aged women with an extensive experience of social and health care. The owners of the older enterprises were more pessimistic about the future than the owners of the more recently-established firms. Social workers have not been active in setting up firms, but the public–private processes should be steered and evaluated from the social work perspective, too, because they are actors who have a relevant part to play in the long-term co-operation and development work of public and private social services.     

Interaction between employees' physical load factors and early support at the workplace

Physical workload is a continuous problem, even in modern workplaces. The purpose of the survey was to determine the effect of support on employees' physical load factors at workplaces. Training, guidance and support were the main focus areas of the early support intervention, which aimed to enable supervisors to find weak signals of impaired ergonomics.The survey was carried out in the form of a controlled longitudinal study, and the material was gathered via a questionnaire in both 2008 and 2010 from two co-operative trade groups. The final sample was 301 intervention subjects and 235 control subjects, and the response rate was 45% in both groups. We applied factor analysis to reduce the number of items. The physical load factors' sum score consisted of six items. We used logistic regression in the statistical analysis.Encouragement to improve processes at the workplace increased the probability of positive change (i.e. decrease) in physical load factors. The same applied to working pace, if individuals could control it themselves. In contrast, workload and the support of supervisors had a reversed impact on workers' physical load factors. Focusing on promoting workers' ergonomics is still important in workplaces when aiming to decrease physical load factors.     

Cash versus Child Care Services in Finland

In 1985 the Finnish Parliament passed a law which stipulated that all children under age three were to be guaranteed a day care place as from the beginning of the 1990s. The law was made possible by a political compromise in which the agrarian Centre Party won the backing it needed to push through a system of state subsidies for the home care of children. As an alternative to a day care place, parents were now given the option of taking a child home care allowance and using that allowance either for purposes of looking after their child themselves or for paying for a private place. Measured in terms of the number of users, the child home care allowance was a hugely successful innovation. Most parents of small children have used the allowance for at least some period of time. This was due above all to the size of the allowance compared with other social benefits. However, following cutbacks in allowance expenditure of more than 20 per cent from 1995, the use of home care allowances declined at almost the same rate as the allowances were reduced. This brought significant short-term savings to the Government and to local authorities, but in the longer term other costs have been rising. There has even been a sharp, unexpected decline in the birth rate. The case of Finland goes to show that, even in a country where wage-earning motherhood has become firmly established, income transfers through family policy can have a very significant influence on the numbers opting temporarily for homemaking.     

Caries on Permanent Teeth: A Non-parametric Bayesian Analysis

Most earlier epidemiological investigations of dental caries have been based on cross-sectional data. Subject-specific information of dental caries in the past, and the duration of exposure of each tooth to the oral environment, are obviously important factors also influencing the presence of dental caries in the future. This has led us to consider multivariate survival models in which the information about the tooth eruption and failure times are combined to assess caries risk. A non-parametric Bayesian intensity model is presented, reflecting, on the one hand, the within subject and between subject sources of variability, and a corresponding split of variability when considering the 28 permanent teeth. We analyse a data set consisting of the dental history of 240 boys, where the observations are based on predetermined dental examinations taking place approximately once every year. Markov chain Monte Carlo integration techniques are applied in the numerical work.