Multiple comparisons based on a modified one-step M-estimator

Although many methods are available for performing multiple comparisons based on some measure of location, most can be unsatisfactory in at least some situations, in simulations when sample sizes are small, say less than or equal to twenty. That is, the actual Type I error probability can substantially exceed the nominal level, and for some methods the actual Type I error probability can be well below the nominal level, suggesting that power might be relatively poor. In addition, all methods based on means can have relatively low power under arbitrarily small departures from normality. Currently, a method based on 20% trimmed means and a percentile bootstrap method performs relatively well (Wilcox, in press). However, symmetric trimming was used, even when sampling from a highly skewed distribution and a rigid adherence to 20% trimming can result in low efficiency when a distribution is sufficiently heavy-tailed. Robust M-estimators are more flexible but they can be unsatisfactory in terms of Type I errors when sample sizes are small. This paper describes an alternative approach based on a modified one-step M-estimator that introduces more flexibility than a trimmed mean but provides better control over Type I error probabilities compared with using a one-step M-estimator.     

Shake,Rattle, and … One or Two Objects? Young Infants' Use of Auditory Information to Individuate Objects

Most research on object individuation in infants has focused on the visual domain. Yet the problem of object individuation is not unique to the visual system, but shared by other sensory modalities. This research examined 4.5‐month‐old infants' capacity to use auditory information to individuate objects. Infants were presented with events in which they heard 2 distinct sounds, separated by a temporal gap, emanate from behind a wide screen; the screen was then lowered to reveal 1 or 2 objects. Longer looking to the 1‐ than 2‐object display was taken as evidence that the infants (a) interpreted the auditory event as involving 2 objects and (b) found the presence of only 1 object when the screen was lowered unexpected. The results indicated that the infants used sounds produced by rattles, but not sounds produced by an electronic keyboard, as the basis for object individuation (Experiments 1 and 2). Data collected with adult participants revealed that adults are also more sensitive to rattle sounds than electronic tones. A final experiment assessed conditions under which young infants attend to rattle sounds (Experiment 3). Collectively, the outcomes of these experiments suggest that infants and adults are more likely to use some sounds than others as the basis for individuating objects. We propose that these results reflect a processing bias to attend to sounds that reveal something about the physical properties of an object—sounds that are obviously linked to object structure—when determining object identity.     

Religion,Convention, and Paternal Involvement

Family scholarship has generally overlooked the influence that religion may have on paternal involvement. Accordingly, using longitudinal data taken from the National Survey of Families and Households, I examined the influence of religious affiliation and attendance on the involvement of residential fathers in one‐on‐one activities, dinner with their families, and youth activities and found religious effects for each of these three measures. Virtually no evidence was found for a competing hypothesis that these effects are artifacts of a conventional habitus such that the type of men who are more conventional in their patterns of civic engagement are both more religious and more involved with their children. However, civic engagement is positively related to paternal involvement.     

Confidence intervals for prediction intervals

When working with a single random variable, the simplest and most obvious approach when estimating a 1???γ prediction interval, is to estimate the γ/2 and 1???γ/2 quantiles. The paper compares the small-sample properties of several methods aimed at estimating an interval that contains the 1???γ prediction interval with probability 1???α. In effect, the goal is to compute a 1???α confidence interval for the true 1???γ prediction interval. The only successful method when the sample size is small is based in part on an adaptive kernel estimate of the underlying density. Some simulation results are reported on how an extension to non-parametric regression performs, based on a so-called running interval smoother.     

Living and loving "decent": religion and relationship quality among urban parents

Religious participation is linked to overall satisfaction among both married and unmarried couples in urban America. Less is known about what may account for the association between religious participation and relationship quality. We explore this issue using data from the first two waves of the Fragile Families and Child Wellbeing Study. Relationship-related behaviors (e.g., temperance) and relationship-specific behaviors (e.g., affection) can each account for the association between church attendance and relationship quality. Furthermore, religious participation appears to be more tightly linked to men's perceptions of relationship quality than women's.     

The denial of emergency protection: factors associated with court decision making

Despite the importance of civil orders of protection as a legal resource for victims of intimate partner violence, research is limited in this area, and most studies focus on the process following a court's initial issuance of an emergency order. The purpose of this study is to address a major gap in the literature by examining cases where victims of intimate partner violence are denied access to temporary orders of protection. The study sample included a review of 2,205 petitions that had been denied by a Kentucky court during the 2003 fiscal year. The study offers important insights into the characteristics of petitioners and respondents to denied orders and outlines individual, contextual, structural, qualitative/perceptual, and procedural factors associated with the denial of temporary or emergency protective orders. Recommendations for statutory changes, judicial education, and future research to remedy barriers to protection are offered.     

The impact of cigarette quitting during pregnancy on other prenatal health behaviors

Several economic studies have evaluated the effects of cigarette smoking and quitting on other health behaviors such as alcohol use and weight gain. However, there is little research that evaluates the effects of cigarette quitting during pregnancy on other health behaviors such as caloric intake, alcohol consumption, multivitamin use, and caffeine intake. In this paper, we evaluate these effects and employ a genetic variant that predicts cigarette quitting to aid in identification. We find some evidence that cigarette quitting during pregnancy may increase multivitamin use and caloric intake and reduce caffeine consumption.     

Comparing variances and means when distributions have non-identical shapes

The paper compares several methods for computing robust 1-α confidence intervals for σ ₁ ²-σ ₂ ², or σ ₁ ²/σ ₂ ², where σ ₁ ² and σ ₂ ² are the population variances corresponding to two independent treatment groups. The emphasis is on a Box-Scheffe approach when distributions have different shapes, and so the results reported here have implications about comparing means. The main result is that for unequal sample sizes, a Box-Scheffe approach can be considerably less robust than indicated by past investigations. Several other procedures for comparing variances, not based on a Box-Scheffe approach, were also examined and found to be highly unsatisfactory although previously published papers found them to be robust when the distributions have identical shapes. Included is a new result on why the procedures examined here are not robust, and an illustration that increasing σ ₁ ²-σ ₂ ² can reduce power in certain situations. Constants needed to apply Dunnett’s robust comparison of means are included.