Disentangling the sources of variation in the survival of the European dipper

The population growth rate of the European dipper has been shown to decrease with winter temperature and population size. We examine here the demographic mechanism for this effect by analysing how these factors affect the survival rate. Using more than 20 years of capture-mark-recapture data (1974-1997) based on more than 4000 marked individuals, we perform analyses using open capture-mark-recapture models. This allowed us to estimate the annual apparent survival rates (probability of surviving and staying on the study site from one year to the next one) and the recapture probabilities. We partitioned the variance of the apparent survival rates into sampling variance and process variance using random effects models, and investigated which variables best accounted for temporal process variation. Adult males and females had similar apparent survival rates, with an average of 0.52 and a coefficient of variation of 40%. Chick apparent survival was lower, averaging 0.06 with a coefficient of variation of 42%. Eighty percent of the variance in apparent survival rates was explained by winter temperature and population size for adults and 48% by winter temperature for chicks. The process variance outweighed the sampling variance both for chick and adult survival rates, which explained that shrunk estimates obtained under random effects models were close to MLE estimates. A large proportion of the annual variation in the apparent survival rate of chicks appears to be explained by inter-year differences in dispersal rates.     

Detection of biomass change in a Norwegian mountain forest area using small footprint airborne laser scanner data

Different approaches for estimation of change in biomass between two points in time by means of airborne laser scanner data were tested. Both field and laser data were collected at two occasions on 52 sample plots in a mountain forest in southeastern Norway. In the first approach, biomass change was estimated as the difference between predicted biomass for the two measurement occasions. Joint models for the biomass at both occasions were fitted using different height and density variables from laser data as explanatory variables. The second approach modelled the observed change directly using the change in different variables extracted from the laser data as explanatory variables. In the third approach we modelled the relative change in biomass. The explanatory variables were also expressed as relative change between measurement occasions. In all approaches we allowed spline terms to be entered. We also investigated the aptness of models for which the residual variance was modeled by allowing it to be proportional to the area of the plot on which biomass was assessed. All alternative models were initially assessed by AIC. All models were also evaluated by estimating biomass change on the model development data. This evaluation indicated that the two direct approaches (approach 2 and 3) were better than relying on modeling biomass at both occasions and taking change as the difference between biomass estimates. Approach 2 seemed to be slightly better than approach 3 based on assessments of bias in the evaluation.     

Life at Trastad Gård: on the experiences of the former inmates of a large institution for people with learning difficulties in northern Norway

In Norway, institutionalised care for people with learning disabilities ended in the 1990s. The aim of this article is to discuss the living conditions at Trastad Gård as described by some of its former inmates. The biographical approach was adopted to capture and discuss the experiences of six former inmates at the institution. Four main but interconnected issues evolving from the stories of our informants were discussed. These include their experiences on coming to the institution, feelings of homesickness, loneliness and lessons of everyday life. The findings were primarily discussed with reference to theoretical perspectives of power and power relations.     

Sensitivity analysis for unmeasured confounding in a marginal structural Cox proportional hazards model

Sensitivity analysis for unmeasured confounding should be reported more often, especially in observational studies. In the standard Cox proportional hazards model, this requires substantial assumptions and can be computationally difficult. The marginal structural Cox proportional hazards model (Cox proportional hazards MSM) with inverse probability weighting has several advantages compared to the standard Cox model, including situations with only one assessment of exposure (point exposure) and time-independent confounders. We describe how simple computations provide sensitivity for unmeasured confounding in a Cox proportional hazards MSM with point exposure. This is achieved by translating the general framework for sensitivity analysis for MSMs by Robins and colleagues to survival time data. Instead of bias-corrected observations, we correct the hazard rate to adjust for a specified amount of unmeasured confounding. As an additional bonus, the Cox proportional hazards MSM is robust against bias from differential loss to follow-up. As an illustration, the Cox proportional hazards MSM was applied in a reanalysis of the association between smoking and depression in a population-based cohort of Norwegian adults. The association was moderately sensitive for unmeasured confounding.     

Residential Concentration Among Immigrants in Oslo

On the basis of register data, this article outlines the development ofresidential concentrations among immigrants in Oslo from the early 1970suntil 1996.
It is argued that a phase characterized by concentrated immigrant housing inthe inner city was superseded by a phase of dispersal which, in turn, was replaced by a period of new concentration. Western and non-Western immigrants live in different parts of the city and the degree of residential concentration varies according to the national background of the immigrants.
Between 1988 and 1993 there was a net flux of non-Western immigrantsfrom the inner city east to the old and new suburban dormitory towns on theoutskirts of the city. This is interpreted as a tendency over time to conformto mainstream Norwegian residential patterns.
The relevance of the term "ghetto" as a designation of areas in Oslo characterized by a high proportion of immigrants is refuted.
Empirical evidence supports the notion that economic resources is the mostimportant factor in creating and maintaining immigrant residential concentrations in the inner city east, while cultural phenomena also appear to play a major causal role.     

Trends in Development Aid,Negotiation Processes and NGO Policy Change

Non-governmental organizations (NGO) and government donor agencies (GDA) are often caught in a dilemma; an NGO between responsiveness to its target group(s), expectations of individual donors and demands of its GDA; GDA between its policy to respect NGO’s integrity, its wish to keep NGOs accountable for received fund and its operation within the bounds of its general policies. This dilemma is mirrored in the NGO–GDA negotiation for funds. Based on negotiation theory and using three explanatory approaches, 18 years of negotiations between an NGO, Vi Skogen (ViS) and its GDA, the Swedish International Development Cooperation Agency (Sida), are analyzed in order to demonstrate how organizational structures, power relations and the context influence the outcome of the negotiations. All three approaches help to explain how ViS managed, mainly in the interest of its individual donors, to resist changes demanded by Sida and also to explain how the agendas of ViS and Sida finally converged.     

The transition from in-home services to out-of-home care: A Danish register-based study

Objective

This register-based study describes the transition from in home-based care to placements in out-of-home care. It also describes whether children who enter care directly differ from children who enter care after episodes of in home-based care.

Method

The study includes all children who entered the child protection system of a larger regional social service system in Denmark from 1993 to 2006 (N = 9961). Graphs of cumulative incidences were used to describe transitions into out-of-home care within two years after in home-based care started. Cox regression models are used to estimate the impacts of child and parental characteristics. In addition, Chi² tests are used to identify differences between children who enter care directly and children who receive in home-based care.

Results

Results indicate that the majority of children do not enter out-of-home care but that risks differ among age groups. Covariates did not predict transitions into out-of-home care for those who entered in-home care after becoming teenagers. Especially for those who entered in-home care before entering their teens, the psychiatric histories of the mothers and the children predicted the transitions into out-of-home care. Immigration background was a protective factor for those who entered in-home care as pre-scholars. Depending on the age group, low birth weight, children's fathers' and mothers' psychiatric histories, and single parentship were all characteristics more likely to be associated with children who entered care directly. Children who entered care directly differed from children who entered care within two years after an in home-based service had been initiated on covariates that described psychiatric history.     

Problem gambling in poker: money,rationality and control in a skill-based social game

The article explores problem gambling in poker. The distinctions between chance and skill and between bank games and social games are applied to demonstrate how poker is structurally different from most other gambling games. Bank games are organised around a central actor such as the house, the casino or the bookmaker. In social games, players compete against each other on equal statistical footing. Poker is a skill-based social game where players with superior skills may be expected to win even in the long run. Fourteen poker playing problem gamblers were recruited through a treatment program and 15 professional and recreational poker players were recruited through snowball sampling (N = 29). Through qualitative interviews, the paper shows that the particular structural composition of poker has implications for the ways problem gambling arises in poker players. It is argued that poker challenges existing theoretical conceptions about problem gambling relating to money, rationality and control.     

Integer‐valued Trawl Processes: A Class of Stationary Infinitely Divisible Processes

This paper introduces a new continuous‐time framework for modelling serially correlated count and integer‐valued data. The key component in our new model is the class of integer‐valued trawl processes, which are serially correlated, stationary, infinitely divisible processes. We analyse the probabilistic properties of such processes in detail and, in addition, study volatility modulation and multivariate extensions within the new modelling framework. Moreover, we describe how the parameters of a trawl process can be estimated and obtain promising estimation results in our simulation study. Finally, we apply our new modelling framework to high‐frequency financial data.     

Econometric Analysis of Realized Covariation: High Frequency Based Covariance,Regression, and Correlation in Financial Economics

This paper analyses multivariate high frequency financial data using realized covariation. We provide a new asymptotic distribution theory for standard methods such as regression, correlation analysis, and covariance. It will be based on a fixed interval of time (e.g., a day or week), allowing the number of high frequency returns during this period to go to infinity. Our analysis allows us to study how high frequency correlations, regressions, and covariances change through time. In particular we provide confidence intervals for each of these quantities.