Adolescents' beliefs about marijuana use: a comparison of regular users, past users and never/occasional users

A questionnaire investigating adolescents' opinions and experiences regarding marijuana use was administered to 163 adolescents and young adults (96 boys and 67 girls) aged 13 to 20 (mean age = 16.8, s.d. = 1.5). Items referred to marijuana and other substances' dangerousness, representations regarding the positive and negative consequences of marijuana use. Responses were compared according to marijuana use status (classified into never/occasional use, current regular use and past regular use). Results show that adolescents' opinions differ according to their experience with marijuana use. Current regular users evaluate marijuana as less dangerous, but alcohol and heroin as more dangerous in comparison with never/occasional and past users. Current and past users are more likely to define marijuana as a medical drug and a plant used in agriculture, and less likely to define it as an illegal drug. Current and past users evaluate marijuana use as a way to cope with stress, to relax to a greater extent than do never/occasional users do. The latter attribute more negative consequences to marijuana use such as diminished driving ability and school performance and a pathway to hard drugs.     

Force steadiness in the lower extremities as an independent predictor of functional performance in older women

The relationship between isometric force control and functional performance is unknown. Submaximal steadiness and accuracy were measured during a constant force-matching task at 50% of maximal isometric voluntary contraction (MVC) of the knee extensors in 19 older women (70-89 years). Other variables included MVC, rate of torque development, and EMG activity. Functional performance was assessed during maximal performance of walking endurance, chair rising, and stair climbing. Isometric steadiness (but not accuracy) was found to independently predict chair-rise time and stair-climbing power and explained more variance in these tasks than any other variable. Walking endurance was related to muscle strength but not steadiness. These results suggest that steadiness is an independent predictor of brief, stressful functional-performance tasks in older women with mild functional impairment. Thus, improving steadiness might help reduce functional limitations or disability in older adults.     

Empirical testing of the expected utility model

Suppose an individual is faced with a set of alternatives with uncertain money outcomes, then according to the expected utilily moded the alternative with the highest cxpected utility will be chosen. In the present paper this model is tested against the more general model given by Kahneman and Iversky (1979) and others. As contrasted with usual practice, the test is based on an exogenously measured utility function. The result of the test is that the expected utility model has to be rejected, both for a concavee and for an S-shaped specification of the utility function. The subjective evaluation of an objectve probability of 0.5 is in this study estimated at a value of 0.45 or 0.47. depending on the functional specification used.Our main conclusion is that although the hypotlicsis of expected utility has to be rejected, for practical purposes the difference between 0.5 and 0.45 (0.47) is so slight, that the hypothesis is a good working approximation. We do not know whether this remains true for valus of the objective probability considerably different from 0.5.     

The impartial culture maximizes the probability of majority cycles

Many papers have studied the probability of majority cycles, also called the Condorcet paradox, using the impartial culture or related distributional assumptions. While it is widely acknowledged that the impartial culture is unrealistic, conclusions drawn from the impartial culture are nevertheless still widely advertised and reproduced in textbooks. We demonstrate that the impartial culture is the worst case scenario among a very broad range of possible voter preference distributions. More specifically, any deviation from the impartial culture over linear orders reduces the probability of majority cycles in infinite samples unless the culture from which we sample is itself inherently intransitive. We prove this statement for the case of three candidates and we provide arguments for the conjecture that it extends to any number of candidates.All three authors thank the Fuqua School of Business for supporting their research collaboration. Regenwetter and Grofman gratefully acknowledge the precious support of the National Science Foundation through grant #SBR-9730076 on Probabilistic Models of Social Choice (Methodology, Measurement and Statistics program). We are grateful to the referees and we thank Saa Peke for critical comments on an earlier draft. Grofman thanks Scott L. Feld for numerous reminders about the implausibility of the impartial culture assumption which helped lead to this paper.     

Residential treatment: linkage with community drug treatment programs.

The realization that the program and services offered at the residential treatment center were not fully effective for some clients with multiple problems was an emotionally wrenching, but unavoidable, process. As the need for outside community substance-abuse referrals continues, it is important that ongoing relationships among agencies be established and nurtured. Dilemmas in creating these relationships have to be expected by all involved. Ways to resolve these problems must be put in place as quickly as they occur. Windows of opportunity to help residential treatment center clients with drug and alcohol problems must be recognized early on in treatment to ensure optimal services. Agencies must coordinate and cooperate with each other to be in position to seize these opportunities when they arise.     

Pediatrics: The emerging psychosocial challenges of the AIDS epidemic

HIV has a pervasive and profound effect on the psychological, social and neuropsychological functioning of infected infants, children and their families. This article discusses direct and indirect psychological manifestations of HIV in children. Direct effects are the outcome of the virus acting on the central nervous system and can result in compromised cognitive, language, motor, socio-emotional and motivational functioning. Indirect effects involve psychological responses to the stress of living with a life threatening illness, the social ostracism, disruption in life goals and undergoing frequent invasive and protracted medical procedures. A major focus of this article is to outline and describe a model comprehensive psychosocial support system developed within the Pediatric Branch of the National Cancer Institute. This includes early intervention issues and strategies for working with families during the introductory phase of the treatment program that also provides the framework for a care management approach, salient mental health problems that frequently occur in this group, and appropriate interventions for individuals and families. Attention is also given to dealing with anticipatory loss and bereavement, implementing traditional innovative intervention techniques, and for providing advocacy services concerning possible legal, financial, housing, and educational issues.     

PARAMETER ESTIMATION FOR LOW-ORDER AUTO-REGRESSIVE MODELS WITH MISSING VALUES

Longitudinal data analysis in epidemiological settings is complicated by large multiplicities of short time series and the occurrence of missing observations. To handle such difficulties Rosner & Muñoz (1988) developed a weighted non-linear least squares algorithm for estimating parameters for first-order autoregressive (AR1) processes with time-varying covariates. This method proved efficient when compared to complete case procedures. Here that work is extended by (1) introducing a different estimation procedure based on the EM algorithm, and (2) formulating estimation techniques for second-order autoregressive models. The second development is important because some of the intended areas of application (adult pulmonary function decline, childhood blood pressure) have autocorrelation functions which decay more slowly than the geometric rate imposed by an AR1 model. Simulation studies are used to compare the three methodologies (non-linear, EM based and complete case) with respect to bias, efficiency and coverage both in the presence and in the absence of time-varying covariates. Differing degrees and mechanisms of missingness are examined. Preliminary results indicate the non-linear approach to be the method of choice: it has high efficiency and is easily implemented. An illustrative example concerning pulmonary function decline in the Netherlands is analyzed using this method.