The economics of adding and subdividing independent risks: Some comparative statics results

In this paper we address the problem of determining whether adding independent risks or subdividing them is a good substitute for insurance. Despite the fact that accepting more i.i.d. risks increases total risk, it is shown that some risk-averse decision makers can rationally reduce their demand for insurance by doing so. Similarly, a better diversified portfolio of i.i.d. risky assets can rationally be more insured, even if diversification is a risk-reduction scheme. We derive conditions sufficient to obtain unambiguous comparative statics results. Assuming that absolute risk aversion is decreasing and that the fourth derivative of the utility function is positive, we show that diversification is an exceptionally good substitute for insurance. Under the same conditions, adding independent risks to wealth reduces the demand for insurance on each unit.     

Differences in the Seriousness of Problems and Deservingness of Help: Swedish Social Workers' Assessments of Single Mothers and Fathers

In this vignette study, three hypotheses concerning differencesin social workers’ assessment off single fathers and mothersare tested: first, that single fathers with custody of theirchildren, who have problems similar to those often faced bysingle mothers, are assessed as having more serious problemsthan the mothers; secondly, that single fathers in such a situationtend to be assessed as being less deserving of support thansingle mothers in the same situation; thirdly, that the helpoffered to both sexes follows gender-traditional patterns. Theresults support the hypotheses. The overall problems and mentalhealth tended to be assessed as more serious in the case ofthe father than in the case of the mother. The single fatherwas assessed as being more responsible for his situation. Thesingle mother was assessed as being in need of assistance inmore areas and more varied social welfare measures were recommendedfor her than for the father. Finally, the results also showthat only support which could enable the client to obtain paidwork and be able to pay off the debts on his car was given higherpriority in the case of the father.     

Writing Distinction – Eine illegitime Kultur als subkulturelles Feld

Graffiti is an illegitimate culture, yet with high potential for distinction and abstract aesthetic principles. The article considers these characteristics as result of the process of the autonomization of graffiti as subcultural field and aims to reconstruct its field logic.     

Mobility and sociality in proximity-sensitive digital urban ecologies: ‘Timid encounters’ and ‘seam-sensitive walks’

This paper is a case study of the use of a proximity-sensitive game played on mobile gaming terminals, in Japan and in France, Dragon Quest 9, and of distinctive forms of mobility and urban encounters which emerge around it. We show how players, when assembled together, walk the ‘connected walk,’ that is they adopt a particular gait, slower than the usual walking pace, with repeated pauses which appears as a tentative and exploratory kind of mobility oriented towards the random occurrence of proximity-based screen-mediated events, and therefore both adjusted to and constitutive of the proximity-sensitive hybrid ecology as a serendipitous place, to be experienced as such. With respect to urban encounters, we have identified a characteristic tension, relevant to locative media in general, in which concerns with potential identification and recognition ‘in the game’ contrasts with the interaction order of urban traffic encounters, characterized by ‘civil inattention.’ This gives rise to the phenomenon of ‘timid encounters,’ in which players strive to experience game encounters with other players a few meters away, while trying to elude visual or verbal recognition.     

Estimation of Causal Odds of Concordance using the Aalen Additive Model

A simple summary of a treatment effect is attractive, which is part of the explanation of the success of the Cox model when analysing time‐to‐event data since the relative risk measure is such a convenient summary measure. In practice, however, the Cox model may fail to give a reasonable fit, very often because of time‐changing treatment effect. The Aalen additive hazards model may be a good alternative as time‐changing effects are easily modelled within this model, but results are then evidently more complicated to communicate. In such situations, the odds of concordance measure (OC) is a convenient way of communicating results, and recently Martinussen & Pipper (2012) showed how a variant of the OC measure may be estimated based on the Aalen additive hazards model. In this study, we propose an estimator that should be preferred in observational studies as it always estimates the causal effect on the chosen scale, only assuming that there are no un‐measured confounders. The resulting estimator is shown to be consistent and asymptotically normal, and an estimator of its limiting variance is provided. Two real applications are provided.     

On perfect simulation for some mixtures of distributions

This paper studies the implementation of the coupling from the past (CFTP) method of Propp and Wilson (1996) in the set-up of two and three component mixtures with known components and unknown weights. We show that monotonicity structures can be exhibited in both cases, but that CFTP can still be costly for three component mixtures. We conclude with a simulation experiment exhibiting an almost perfect sampling scheme where we only consider a subset of the exhaustive set of starting values.