Frailty models are the survival data analog to regression models, which account for heterogeneity and random effects. A frailty is a latent multiplicative effect on the hazard function and is assumed to have unit mean and variance θ, which is estimated along with the other model parameters. A frailty model is an heterogeneity model where the frailties are assumed to be individual-or spell-specific. A shared frailty model is a random effects model where the frailties are common (or shared) among groups of individuals or spells and are randomly distributed across groups. Parametric frailty models were made available in Stata with the release of Stata 7, while parametric shared frailty models were made available in a recent series of updates. This article serves as a primer to those fitting parametric frailty models in Stata via the streg command. Frailty models are compared to shared frailty models, and both are shown to be equivalent in certain situations. The user-specified form of the distribution of the frailties (whether gamma or inverse Gaussian) is shown to subtly affect the interpretation of the results. Methods for obtaining predictions that are either conditional or unconditional on the frailty are discussed. An example that analyzes the time to recurrence of infection after catheter insertion in kidney patients is studied.
Three experiments investigated the relationship between the presumption of harm in harmfree violations of creatural norms (taboos) and the moral emotions of anger and disgust. In Experiment 1, participants made a presumption of harm to others from taboo violations, even in conditions described as harmless and not involving other people; this presumption was predicted by anger and not disgust. Experiment 2 manipulated taboo violation and included a cognitive load task to clarify the post hoc nature of presumption of harm. Experiment 3 was similar but more accurately measured presumed harm. In Experiments 2 and 3, only without load was symbolic harm presumed, indicating its post hoc function to justify moral anger, which was not affected by load. In general, manipulations of harmfulness to others predicted moral anger better than moral disgust, whereas manipulations of taboo predicted disgust better. The presumption of harm was found on measures of symbolic rather than actual harm when a choice existed. These studies clarify understanding of the relationship between emotions and their justification when people consider victimless, offensive acts.
This research tests how perceived school and peer norms predict interethnic experiences among ethnic minority and majority youth. With studies in Chile (654 nonindigenous and 244 Mapuche students, M = 11.20 and 11.31 years) and the United States (468 non-Hispanic White and 126 Latino students, M = 11.66 and 11.68 years), cross-sectional results showed that peer norms predicted greater comfort in intergroup contact, interest in cross-ethnic friendships, and higher contact quality, whereas longitudinal results showed that school norms predicted greater interest in cross-ethnic friendships over time. Distinct effects of school and peer norms were also observed for ethnic minority and majority youth in relation to perceived discrimination, suggesting differences in how they experience cross-ethnic relations within school environments.
Do verbal reports of disgust in moral situations correspond to the concept of disgust as measured by other means, or are they used metaphorically to refer to anger? In this experiment, participants read scenarios describing a violation of a norm either about the use of the body (bodily-moral) or about harm and rights (socio-moral). They then expressed disgust and anger on verbal scales, and alternate representations of these emotion concepts were assessed through facial expression endorsement measures. When socio-moral norms were violated, anger words strongly predicted disgust words, and the separate role of disgust face endorsement was low, although significant. When bodily norms were violated, the predictive role of anger words roughly equaled the role of disgust face endorsements. Angry faces, however, never predicted disgust words independently of anger words. These results support a middle ground position in which disgust words concerning socio-moral violations are not entirely a metaphor for anger and bear some relationship to other representations of disgust. At the same time, however, the use of disgust language is more strongly related to anger language, and less strongly related to facial representations of disgust, for socio-moral versus bodily-moral violations.
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