What are randomised controlled trials good for?

Randomized controlled trials (RCTs) are widely taken as the gold standard for establishing causal conclusions. Ideally conducted they ensure that the treatment ‘causes’ the outcome—in the experiment. But where else? This is the venerable question of external validity. I point out that the question comes in two importantly different forms: Is the specific causal conclusion warranted by the experiment true in a target situation? What will be the result of implementing the treatment there? This paper explains how the probabilistic theory of causality implies that RCTs can establish causal conclusions and thereby provides an account of what exactly that causal conclusion is. Clarifying the exact form of the conclusion shows just what is necessary for it to hold in a new setting and also how much more is needed to see what the actual outcome would be there were the treatment implemented.     

Does Roush show that evidence should be probable?

This paper critically analyzes Sherrilyn Roush’s (Tracking truth: knowledge, evidence and science, 2005) definition of evidence and especially her powerful defence that in the ideal, a claim should be probable to be evidence for anything. We suggest that Roush treats not one sense of ‘evidence’ but three: relevance, leveraging and grounds for knowledge; and that different parts of her argument fare differently with respect to different senses. For relevance, we argue that probable evidence is sufficient but not necessary for Roush’s own two criteria of evidence to be met. With respect to grounds for knowledge, we agree that high probability evidence is indeed ideal for the central reason Roush gives: When believing a hypothesis on the basis of e it is desirable that e be probable. But we maintain that her further argument that Bayesians need probable evidence to warrant the method they recommend for belief revision rests on a mistaken interpretation of Bayesian conditionalization. Moreover, we argue that attempts to reconcile Roush’s arguments with Bayesianism fail. For leveraging, which we agree is a matter of great importance, the requirement that evidence be probable suffices for leveraging to the probability of the hypothesis if either one of Roush’s two criteria for evidence are met. Insisting on both then seems excessive. To finish, we show how evidence, as Roush defines it, can fail to track the hypothesis. This can remedied by adding a requirement that evidence be probable, suggesting another rationale for taking probable evidence as ideal—but only for a grounds-for-knowledge sense of evidence.     

Relations of proactive and reactive dimensions of aggression to overt and covert narcissism in nonclinical adolescents

In recent years, there has been increasing acknowledgment of the multidimensionality of narcissism and that different types of narcissism may relate differently to other domains of functioning. Similarly, aggression—a frequently discussed correlate of narcissism—is a heterogeneous construct. In this study, the relations of proactive and reactive aggression with overt and covert manifestations of narcissism were examined in a sample of 674 Italian high school students (mean age=15.5 years, SD=2.1 years). Overt narcissism was positively related to both proactive and reactive subtypes of aggression, whereas covert narcissism related only to reactive aggression. Vanity, Authority, Exhibitionism, and Exploitativeness were the components of overt narcissism related to Proactive Aggression (all remained unique correlates when controlling for Reactive Aggression), whereas Reactive Aggression was associated with the Exhibitionism, Superiority, and Entitlement subscales (only the latter was uniquely related when controlling for Proactive Aggression). Aggr. Behav. 36:21–27, 2010. © 2009 Wiley‐Liss, Inc.     

Creativity and achievement in design coursework

Abstract:

Findings from this investigation with 81 college students indicate that ideational fluency is a valid predictor of student achievement in an interior design course. Both original and popular ideational fluency as measured by the Multidimensional Stimulus Fluency Measure were related to the course grade, design criteria scores, and the final project grade. Very few studies have found such a clear relationship between performance on any measure of creativity and actual performance in a course. The results suggest that the MSFM is a valuable tool for use in conjunction with other criteria in admissions screening for an interior design program.     

Gender Comparisons in the Perception of Self-Competence Among Four-Year-Old Children

The purpose of this study was to determine the presence of gender differences in the perception of self-competence among 4-year-old children. Sixty-one 4-year-olds (27 girls and 34 boys) from predominantly European American backgrounds participated in the study. The children's self-competence was measured using the Pictorial Scale of Perceived Competence and Social Acceptance for Young Children (Preschool version; S. Harter & R. Pike, 1984), which has 4 separate subscales: (a) cognitive competence, (b) physical competence, (c) peer acceptance, and (d) maternal acceptance. A within-subject 2-way analysis of variance with repeated measures of 4 (subscales of perception of self-competence) × 2 (gender) was performed to determine if gender differences existed in the children's perception of self-competence. Analyses of the data showed no significant gender differences in the scores on the 4 subscales for the perception of self-competence among the children. These results could be interpreted as being due to a less gender-stereotyped society and androgynous environment for these preschoolers.     

Toddlers' Social Behaviors in Dyads and Groups

Although toddlers are clearly capable of interacting with peers, the amount and type of interactions among toddlers is controversial. Objectives of the present study were (a) to determine the effect of dyad versus group settings on the amount and type of social behaviors with peers, (b) to determine preference for interacting with peers versus adults, and (c) to determine differences in the types of behaviors directed to peers and adults. Sixteen children (with a mean age of 27 months) were observed in both a group setting and a dyad setting; their mothers were present in both settings. The children were from three different toddler classes, each meeting once a week. Specific social behaviors were coded, as well as the person to whom the behavior was directed (i.e., peer or adult). Setting affected toddlers' behaviors with adults but not behaviors with peers. Regardless of setting, toddlers preferred interacting with adults. The types of behaviors directed to peers and adults differed. Direct interactions with peers were rare, but interest and awareness of peers was shown by moderately high levels of proximity and parallel play. The use of different criteria to define social play appears to account for differences across studies in the amount of peer interaction.