Intact Social Groups Research Articles

Fatherlessness by Divorce Contrasted to Fatherlessness by Non-Marital Births

Although “marriage” and the “family” have tended to be analyzed with the individual participants as the frame of reference, recent trends in family-formation have taken a trajectory that clearly affects the community or any intact social group. One such trend is increased levels of father-absence: Preclusion or abrasion of the father from the mother-child dyad. Evidence is presented which argues that father-preclusion and father-abrasion are two separate phenomena from two separate populations. It is also suggested that when long-term relationships between a manhusband and a woman-wife fail to occur within a community that community is subject to a myriad of (reproductive) health and behaviorally related dysfunctions which occur a generation later. Finally, it seems that there is a paucity of developmental theory, which can account for the generation lag between father preclusion and social problems.

Skewed sex ratios and female homosexual activity in Japanese macaques: An experimental analysis.

In this paper we present the results of a behavioral experiment conducted to test whether homosexual consortships and sexual solicitations among female Japanese macaques (Macaca fuscata) increase in the context of operational sex ratios that are heavily skewed towards females. The study involved a baseline period of observation on an intact social group which had a female-biased sex ratio typical of this species. During the experimental period which followed, we created a sub-group with an operational sex ratio that was heavily skewed towards females. Compared to the baseline period, females solicited significantly more same-sex individuals for sex and formed significantly more homosexual consortships during the experimental period of the study. Females did not appear to engage in homosexual activity during the study's experimental period simply because they lacked heterosexual alternatives. Instead, we suggest that an abundance of certain types of preferred, same-sex sexual partners and/or a scarcity of opposite-sex sexual competitors best account for the increased levels of female homosexual behavior observed at this time.

Some Aspects of the Design and Analysis of Cluster Randomization Trials

SUMMARY Trials which randomize intact social groups, or clusters, to different interventions are becoming increasingly widespread. Although statistically less efficient than trials which randomize individuals, such designs are often preferred from a practical or ethical point of view, particularly in the evaluation of health care or educational strategies. We discuss selected issues that arise in the conduct of such trials, including the choice of design, ethical implications, sample size estimation and approaches to the analysis. The discussion is closely tied to methodological issues that have arisen in a recent evaluation trial of a new antenatal care programme, as sponsored by the Special Programme of Research, Development and Research Training in Human Reproduction of the World Health Organization.

A Violence Prevention Curriculum-Reply

In Reply. —Drs Green and Wintfeld appear to have several misunderstandings regarding our study. First, the use of the phrase violence prevention is one that the authors of the curriculum coined. Our study purposes were clear: to determine the effect of the curriculum on some precursors to violence, especially physically and aggressive behavior. Our behavioral observers were trained to score physically aggressive behavior at 2 different levels of intensity. The lower intensity level was called negative physical/nonverbal and included acts such as object struggles, personal property damage, physical threats, aversive physically threatening gestures, physical pestering with protest, and minor physical contact such as shoving and pushing. The higher level of intensity involved violent attacks with body or object.1 Green and Wintfeld's concern regarding whether our study was a randomized controlled trial merits further discussion. The randomized community trial, in which intact social groups are allocated at random to intervention

Intraclass correlation among measures related to tobacco use by adolescents: Estimates, correlates, and applications in intervention studies

Tobacco intervention studies that employ a community trial design require adjustment to the usual analytic methods to account for the allocation of intact social groups to study conditions and the positive intraclass correlation (ϱ) that is inevitable in such a design. In the absence of valid estimates of the relevant ϱ, investigators seeking to establish an appropriate sample size could only guess about the magnitude of the problem. We recently published estimates of ϱ for common measures of adolescent tobacco use, but those estimates were unadjusted for potential covariates and so represented an upper limit on the magnitude of ϱ. This report demonstrates how estimates of intraclass correlation may be substantially reduced through regression adjustment for easily measured covariates. Results show that both the ϱ and the residual variance can be reduced, by an average of 20 and 11%, respectively, offering greater efficiency for investigators who plan future studies and who are able to measure those covariates in their studies. Future work should seek both to replicate this work and to extend it: for example, to cohort designs where the improvements might be even greater.

Design and Analysis Issues in Community-Based Drug Abuse Prevention

This article reviews the design and analysis issues that face community-based drug abuse prevention trials. Such trials allocate intact social groups to study conditions and fall within the general class of studies called “community trials.” Special concerns for community trials include selection bias, differential mortality and maturation, contamination, poorly defined constructs, weak interventions, violation of assumptions underlying analysis methods, and low power. Potential solutions include careful selection of comparison units, tight control over distribution of intervention materials, matching, randomization, adding more units to each condition or more frequent observations in each unit, monitoring exposure to intervention-like activities in all sites, regression adjustment for covariates, modeling time, and selection of an appropriate analysis model. Four approaches to analysis are illustrated in an example based on an adolescent tobacco use prevention study.

Intraclass Correlation among Common Measures of Adolescent Smoking: Estimates, Correlates, and Applications in Smoking Prevention Studies

Most adolescent smoking prevention studies employ designs in which classrooms, schools, school districts, or sometimes whole communities are assigned to treatment conditions while observations are made on individual students. The critical design feature in such community trials is the nesting of intact social groups within treatment conditions. This combination requires that the treatment effect be assessed against the between-group variance; unfortunately, that variance is usually larger than for randomly constituted groups and its precision is usually less than that for the within-group variance. These factors often combine to reduce power so that it is almost impossible to detect important treatment effects in an otherwise well designed and properly executed study. To address these problems, investigators need good estimates of the intraclass correlation for the variables of interest, which together with the number of observations per unit determine the magnitude of the extra variation in the nested design. The purpose of this paper is to describe the methods and results from a study designed to generate estimates of intraclass correlation for common outcomes in adolescent smoking prevention studies and to discuss the use of these estimates in the planning of new studies.

Breeding behaviour of pilot whales revealed by DNA fingerprinting

Most species of whale spend the majority of their lives well away from land, are capable of migrating over large distances and are difficult to identify individually. However, conservation measures require a detailed understanding of their social structure, breeding behaviour and migration patterns. The advent of DNA fingerprinting permits a systematic investigation of such parameters. In the Faeroe Islands there exists a traditional harvest of long-finned pilot whales (Globicephala melas), in which intact social groups (pods) are captured. This affords a unique opportunity to study genetic relationships within and between pods. We report here on a paternity analysis, using DNA fingerprinting, of mother-fetus pairs and males sampled from complete pods. In addition, a single, highly polymorphic minisatellite locus was used to infer degrees of relatedness between groups of fetuses and females. Taken together, our results suggest that pods consist of closely related adult females and their offspring. Sexually mature males either move frequently between pods or remain in their natal pod but refrain from mating with female relatives. Whichever hypothesis is correct, the data suggest that each male spends only a few months with the female post-mating and individual males often father several fetuses within a pod.

Planning for the appropriate analysis in school-based drug-use prevention studies.

School-based drug-use prevention studies often apply interventions to entire schools. A major problem for these studies results from the intragroup dependence often seen when intact social groups are assigned to study conditions. Analysis of data from 2 such studies revealed intraclass correlation coefficients between 0.02 and 0.05 for common drug use measures. Because even such modest intragroup dependence can invalidate the traditional fixed-effects analyses, researchers should adopt alternative methods that acknowledge this dependence. These alternative methods are reviewed, and appropriate methods for computing sample size requirements are illustrated. Investigators should consider these analysis issues when planning future studies, because the number of schools required for an unbiased analysis may be substantially greater than for the traditional methods.

Planning for the appropriate analysis in school-based drug-use prevention studies.

School-based drug-use prevention studies often apply interventions to entire schools. A major problem for these studies results from the intragroup dependence often seen when intact social groups are assigned to study conditions. Analysis of data from 2 such studies revealed intraclass correlation coefficients between 0.02 and 0.05 for common drug use measures. Because even such modest intragroup dependence can invalidate the traditional fixed-effects analyses, researchers should adopt alternative methods that acknowledge this dependence. These alternative methods are reviewed, and appropriate methods for computing sample size requirements are illustrated. Investigators should consider these analysis issues when planning future studies, because the number of schools required for an unbiased analysis may be substantially greater than for the traditional methods.

Validation of sociometric structure by data on individuals' attributes

Longstanding challenges to relate sociometric structure of an intact social group to other social variables are answered first by obtaining a partition of a set of 69 inmates in Cook County Jail, using a clustering algorithm (CONCOR) applied to sociometric data. We then demonstrate that the resulting partition can be accounted for by substantively interpretable variables (e.g. number of years of school prior to incarceration) measured on the individual inmates. The linear discriminant function used to relate the two types of data does a good job of accounting for processes generating sociometric ties of friendship. It is argued that this methodology can be used to study the diversity of inmate organizational structure.