Jerry L. L. Miller

TESTING A DYNAMIC MODEL OF SOCIAL COMPOSITION: DIVERSITY AND CHANGE IN VOLUNTARY GROUPS*

We test a dynamic model of the social composition of voluntary groups. The model is based on the idea that sociodemographic variables define social niches in which voluntary groups grow and decline, share and compete, and change or remain static. The flow of individuals through such groups depends on the competition of other groups for their time and other resources. We build a dynamic model of this process and show how this model can account for changes in the social composition and the social heterogeneity of voluntary groups. We use life history data on the group affiliations of 1,050 individuals from 1974 to 1989 to test hypotheses about the diversity of education among group members and about the mean level of education of the members. Our data strongly support the hypotheses.

The diffusion of collective violence.

Past explanations of violence have characteristically paid more attention to the issues of social conditions and psychocultural stimuli than to the issue of timing. Timing is the focus of this paper in which a differential equation model of the temporal diffusion of violence is developed. This model is derived from behavioral generalizations which indicate that aggression is both instigated and inhibited via direct and vicarious learning. The parameters of the model provide measures of the instigation and inhibition processes that take place throughout an outbreak. Twenty-five data sets representing a wide variety of collective outbreaks of violence are used to test the empirical fit and to evaluate the credibility of the assumptions of the model. The model describes the overtime distribution of incidents quite accurately and the assumptions and implications of the derivation appear to be consistent with the cultural conditions surrounding the outbreaks.

Difficulty: a neglected factor in health promotion.

A series of studies of likelihood of adopting risk-reducing or weight-reduction activities revealed that the perceived difficulty of adoption was a more powerful factor in likelihood of adoption than was perceived effectiveness of the activities. This finding is significant because most intervention programs emphasize convincing clients of the effectiveness of their methods and treat difficulty as a given or a constant. These studies showed not only that difficulty varied, but also that the relationship between likelihood of adopting an activity and the preceived effectiveness and difficulty of the activity was multiplicative and, therefore, curvilinear. At low levels of difficulty, likelihood of adoption was high, but as difficulty increased, likelihood dropped rapidly. The relationship between effectiveness and likelihood, on the other hand, showed small increases in likelihood as effectiveness increased to moderate levels, with little increase at higher levels. These relationships were more pronounced among those for whom the target risk was highly relevant. One implication for practice is that a greater payoff will be realized by reversing the conventional focus of intervention and instead helping clients reduce the difficulty of adopting necessary activities.

Arms Races: A Test of Two Models

This is an investigation of two models of arms races: Lewis F. Richardsons linear, additive, symmetric model and a curvilinear, asymmetric alternative based on the same interaction paradigm but with empirical equations from psychophysical experiments on perception as premises. Two hypotheses derived from each model are tested using data from seven arms races. In general, the data give stronger support to the curvilinear, asymmetric model which predicts the follower in the arms race will increase its armaments through time as an exponential function of the leaders armaments, and the leader will increase its armaments as a power function of the followers efforts at the previous time period. The conclusions are based on the relative fit of the models to the seven sets of data, parsimony, reasonableness of the parameter estimates as adjudged by their signs and magnitudes, and predictions about the outcomes of the races-war or armed truce.

Demographic and health status indicators to guide health promotion for Hispanic and Anglo rural elderly

Naturally occurring differences rather than simple breakdowns by ethnic category are being used to tailor strategies in a three year senior community health worker-delivered health promotion intervention. A survey conducted of persons 60 and over in a rural southwestern U.S. community identified New Anglos (recent settlers, n = 264), Old Anglos (long-time residents, n = 298) and Hispanics (n = 236) for a total of 798 persons. Significant demographic differences included less education, poorer health status and more chronic conditions among Hispanics. Low rates of screening were the norm but especially severe among Old Anglos. Patterned differences in health practices, as well as group variations in use of resources and sources of information, revealed New Anglos used a larger variety of services and media. Generally, adjustments being made are related to Hispanic culture, cosmopolitan orientation of the New Anglos, and long-term isolation from information and services for Old Anglos.