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PubMed1997

A preliminary evaluation of causal models of male and female acquisition of pilot skills.

Based on a previous study, a causal model of acquisition of pilot job knowledge and flying skills was tested on separate samples of male and female students. Causal model parameters were estimated separately for each sample and, due to the small sample size for women, no between-groups statistical tests were conducted. The results are viewed as tentative because of the small sample of female students; however, the path coefficient parameter estimates are still useful. The model showed a direct influence of general cognitive ability (g) on the acquisition of job knowledge and an indirect influence on the acquisition of flying skills. The direct and indirect influence of cognitive ability on flying skills was a little stronger for women than for men. Additionally, the path between prior job knowledge (JKp) and flying performance was somewhat stronger for women than for men. Consistent with previous findings, the influence of early flying skills on later flying skills was very strong. No argument for a sex-separated training syllabus is supported.

Adult↗

PubMed1996

Induced illness in interleukin-6 (IL-6) knock-out mice: a causal role of IL-6 in the development of the low 3,5,3'-triiodothyronine syndrome.

Interleukin-6 (IL-6) administration to human subjects or experimental animals induces changes in thyroid hormone metabolism resembling those in the sick euthyroid syndrome. Furthermore, the decrease in serum T3 during illness is significantly related to serum IL-6 concentrations. These findings suggest, but do not prove, a causal role for IL-6 in the development of the low T3 syndrome. The aim of the present study was to evaluate the role of IL-6 in the development of the sick euthyroid syndrome in IL-6 knock-out (IL-6(-/-)) mice compared to that in wild-type mice (IL-6(+/+)). Illness was induced in IL-6(-/-) and IL-6(+/+) mice by 1) administration of bacterial endotoxin (LPS), 2) infection with Listeria monocytogenes, and 3) turpentine injection in both hind limbs. Food intake was kept similar in both groups in all three experiments. Serial measurements were made of serum IL-6, tumor necrosis factor-alpha, T3, T4, corticosterone, and liver 5'-deiodinase (5'-DI) messenger RNA (mRNA) for 24 h (LPS), 96 h (L. monocytogenes), and 48 h (turpentine). Serum IL-6 increased in response to all stimuli in IL-6(+/+) mice, but not in IL-6(-/-) mice. Serum tumor necrosis factor-alpha was induced by LPS in both groups to a similar extent, but did not rise after L. monocytogenes or turpentine administration. Serum T3 and T4 decreased after all three stimuli. The decrease in serum T4 in IL-6(-/-) was similar to that in IL-6(+/+) mice. The decrease in serum T3, however, was smaller in the IL-6(-/-) mice than in the IL-6(+/+) mice; T3 levels were 1.56 +/- 0.29 and 0.99 +/- 0.15 nmol/liter, respectively, 24 h after LPS treatment (P < 0.01), 2.39 +/- 0.17 and 1.75 +/- 0.24 nmol/liter 96 h after L. monocytogenes treatment (P < 0.01), and 1.46 +/- 0.18 and 1.10 +/- 0.25 nmol/liter 48 h after turpentine treatment (P < 0.05). The smaller fall in serum T3 in IL-6(-/-) mice could not be attributed to differences in the severity of the induced illness, food intake, or corticosterone response, which were all similar in IL-6(-/-) mice and IL-6(+/+) mice. Liver 5'-deiodinase mRNA decreased after all three stimuli; the decrease after LPS and L. monocytogenes infection was smaller in the IL-6(-/-) mice, but the difference in IL-6(+/+) mice just failed to reached statistical significance. Liver 5'-deiodinase activity after turpentine injection administration decreased in the wild-type animals by 36%, but did not change in the knock-out mice. In conclusion, acutely induced illness generates the low T3 syndrome, which is less marked in IL-6 knock-out mice than in wild-type mice. The data suggest a causal role of IL-6 in the development of the low T3 syndrome.

Animals↗

PubMed1981

Disease causality and politics.

This article distinguishes three current theories that purport to account for the etiology of chronic diseases: a germ theory, a lifestyle theory and an environmental theory. Since each of these proposals about disease causality implies a different locus of responsibility for disease prevention, the medical disputes surrounding the theories often mask more fundamental political controversies over the proper organization of society. This article reports briefly on the medical debate accompanying each theory and more fully on the political argument each gives rise to. It concludes with a critique of the multifactorial theory of disease causality, calling it both ineffective and biased against those people most at risk of becoming ill.

Disease↗

PubMed1997

[Causal inference in medicine: a reaction to the report, "incidence of Minamata disease in communities along the Agano River, Niigata, Japan--patterns of the exposure and official diagnosis of patients"].

Kondo's "Incidence of Minamata Disease in Communities along the Agano River, Niigata, Japan (Jap. J. Hyg. 51:599-611;1996)" is critically reviewed. The data of the article were obtained from most of the residents living in the Agano river villages where Minamata disease was discovered in June, 1965. However, sampling proportions were much different between in the population base and in the cases. The method of identification of cases from the data and the reason for the difference were not clearly demonstrated. The citations of reference articles are insufficient despite the fact that other epidemiologic studies on methyl-mercury poisoning have been reported not only in Japan, but also around the world. His "analysis of the recognized patients" is erroneous. Both the sampling scheme of information of hair mercury and the modeling of the analysis are based on Kondo's arbitrary interpretation, not on epidemiologic theory. His "analysis of the rejected applicants" is also erroneous. His calculations of the attributable proportion are incorrect and self-induced in both the assignments of data and analysis of data. Kondo has failed to study the epidemiologic theories in light of changes in the field. Therefore, his article is lacking in epidemiologic theory, a logical base and scientific inference. In Japan, epidemiologic methodology has rarely been used in studies on Minamata Disease in either Kumamoto and Niigata. The government has used neurologically specific diagnosis based on combinations of symptoms to judge the causality between each of symptoms and methyl-mercury poisoning. Epidemiologic data obtained in Minamata, Kumamoto in 1971 indicate that the criteria set by the government in 1977 have produced much more false-negative patients than false-positive patients. As a result, a huge number of symptomatic patients, including those with peripheral neuropathy or with constriction of the visual field, did not receive any help or compensation until 1995. The authors emphasize that the causal relationship between each symptom and methyl-mercury exposure should be reevaluated epidemiologically in Japan.

Epidemiologic Methods↗

PubMed2005

Adjustment to breast cancer: the contribution of resources and causal attributions regarding the illness.

The study examined personal resources (sense of coherence and social support) and attributions concerning the causes of illness, and their relationship to adjustment to breast cancer. The research sample included 60 Israeli women with breast cancer, who responded to questionnaires at two stages of their illness: the stage of initial discovery (after first learning of the illness) and approximately six months later (the stage of mitigation and accommodation). The overall level of adjustment to the illness was moderate. While the patients adjusted relatively well in the family and domestic environments, their adjustment in the dimensions of health care, psychological distress, and sexual relations was relatively low. The most frequent causal attributions were psychological factors and family history of illness. The patients' subjective state of health, sense of coherence, and levels of social support were related to most of the adjustment dimensions examined, although both internal and external causal attributions correlated negatively with adjustment in every dimension.

Adaptation, Psychological↗

PubMed2001

A case-control study of differences between regular and causal adult attenders in general dental practice.

OBJECTIVES: To assess whether adults attending a dental practice for regular dental care have better oral health than adults attending casually in response to a dental problem, and to explore the barriers to asymptomatic attendance. METHODS: An observational case-control study comparing the characteristics of 100 regular attenders with 100 causal attenders in one general dental practice in North Staffordshire. All study subjects were aged 18 years or over. Sociodemographic characteristics of the two groups were collated, including age, gender, social class, marital status, employment status and smoking status. The primary outcome measure was the observed number of teeth with dentinal caries diagnosed using bitewing radiographs. RESULTS: Regular attenders were observed to have better oral health with respect to dental caries and tooth mobility (p < 0.05). This was not explained by the observation that causal attenders were more likely than regular attenders to be male, aged 18-44 years, in social class III or IV. Secondary outcomes, including number of subjects with mobile teeth and teeth with > 30% bone-loss, were also significantly worse in the casual attenders. However, the median number of teeth present in both groups was 27. In regular attenders, the most common reason for attending was to 'keep the teeth' (96%). In casual attenders, 'fear/dislike of dental treatment' was the most frequent indicator of non-attendance (56%). CONCLUSIONS: In our study, adults who regularly attended general dental practice were shown to have better oral health, including less overall tooth decay, mobility and bone-loss, compared with adults who did not attend on a regular basis. Assuming this result to be externally valid, a challenge for the dental profession in the future will be to develop effective oral health promotion initiatives.

Adolescent↗

PubMed2000

Pupils' causal attributions for difficult classroom behaviour.

BACKGROUND: Studies of causal attributions within educational contexts have tended to concentrate on academic performance. There have been a smaller number of investigations of teachers' attributions for pupils' behaviour in school. AIMS: The present study examines the causal attribution made by pupils for difficult behaviour in classrooms. It reveals the structure of these attributions and serves as a comparison with the teacher studies. SAMPLE: The participants were 105 pupils (52 males and 53 females) in the first year of secondary schooling, all drawn from the same inner city school. METHOD: Four initial small group interviews were used to identify a wide range of factors that pupils viewed as being causes of difficult classroom behaviour in the 18 primary schools they had previously attended. A questionnaire was then constructed incorporating items from these discussions and administered to the whole of the year group of pupils, but omitting the participants in the initial group discussions. RESULTS: The results of a factor analysis indicated that pupils' attributions for misbehaviour at school were best represented by four factors: (1) 'fairness of teacher's actions', (2) 'pupil vulnerability', (3) 'adverse family circumstances' and (4) 'strictness of classroom regime'. While there were no gender differences, pupils saw the 'fairness of teacher's actions' and 'pupil vulnerability' as more significant contributors to pupil misbehaviour than either 'adverse family circumstances' or 'strictness of classroom regime'. CONCLUSION: The attributions by pupils for difficult classroom behaviour differ markedly from those obtained in studies of teachers. Policy and practice initiatives which do not attend to conflicting attributional styles are unlikely to succeed in improving levels of pupil behaviour in schools.

Child↗

PubMed2000

Teachers' causal attributions, cognitive, emotional and behavioural responses to students with emotional and behavioural difficulties.

BACKGROUND: The vast majority of children with emotional and behavioural difficulties are educated in their usual classes in ordinary schools across the countries. The study, therefore, of teachers' responses to these children is important for both teachers' and students' well-being in schools. Research provides evidence that teachers attribute students' difficulties to factors external to themselves, that is family or child factors and although they experience feelings of irritation and indifference with disruptive students they feel responsible and committed to help them. As far as their coping strategies are concerned, teachers seem to mostly favour positive interventions. AIMS: This study aimed to examine Greek teachers' causal attributions, emotional and cognitive responses, coping strategies and suggestions for effective coping strategies with students with emotional and behavioural difficulties. SAMPLE: This comprised 391 elementary teachers teaching in 60 public schools in the area of Athens. METHOD: Teachers completed an inventory presenting six short scenarios of students with emotional and behavioural difficulties, varying in the type of difficulty (conduct or emotional) and the degree of severity for teachers to handle them (mild or severe). RESULTS: Repeated-measures ANOVA revealed that teachers perceived school and teacher factors as causal of emotional and behavioural difficulties. Teachers expressed feelings of sympathy for these children, and perceived themselves as responsible, self-efficacious and inclined to help them. Finally, they reported using supportive techniques to handle emotional and behavioural difficulties, which they also considered as effective. CONCLUSIONS: Teacher training becomes crucial as a process of adopting patterns of thought and strategies for responding to students with emotional and behavioural difficulties.

Adaptation, Psychological↗

PubMed2002

Parents' and pupils' causal attributions for difficult classroom behaviour.

BACKGROUND: Studies of causal attributions for difficult pupil behaviour in schools have tended to focus on the perspectives of teachers. AIMS: The present study examines the causal attributions made by parents for difficult behaviour in classrooms. It reveals the structure of these attributions and serves as a direct comparison to a previous study of pupils' attributions (Miller, Ferguson, & Byrne, 2000) and, more indirectly, with the teacher studies. SAMPLE: The participants were 144 parents (106 mothers and 38 fathers) whose children all attended the same inner city school. METHOD: A questionnaire was constructed following three initial small group interviews with parents to identify the wide range of factors they viewed as potential causes of difficult classroom behaviour. This was then administered to all the parents of children attending the same inner-city primary school. RESULTS: Factor analysis indicated that parents' attributions for misbehaviour were best represented by three factors: (1) 'fairness of teachers' actions', (2) 'pupil vulnerability to peer influences and adverse family circumstances', and (3) 'differentiation of classroom demands and expectations'. While there were no differences between parents in terms of gender or ethnicity, they did see the first two factors as more significant contributors to pupil misbehaviour than the third. CONCLUSION: There is both agreement and conflict between parents' attributions and those made by pupils and by teachers. The implementation of policy initiatives, such as home-school agreements and Pastoral Support Programmes, risk exacerbating tensions and difficulties if these differences in attributions are not acknowledged and acted upon.

Child↗

PubMed2002

Beck's cognitive theory of depression: a test of the diathesis-stress and causal mediation components.

OBJECTIVES: This prospective study tested the diathesis-stress and causal mediation components of Beck's (1967, 1983) cognitive theory of depression. DESIGN: In order to allow for a stringent test of the aetiological component of Beck's theory, we used a short-term longitudinal design in which participants' dysfunctional attitudes were assessed prior to the occurrence of a negative event. METHODS: In all, 136 high school seniors applying to the University of Pennsylvania completed measures of depressed mood and dysfunctional attitudes 1-8 weeks before receiving their admissions decision (Time 1). The assessment of dysfunctional attitudes was preceded by a priming task designed to activate latent depressogenic schemata. Participants also completed measures of depressed mood, negative views of the self, and negative views of the future shortly after they received their admissions decision (Time 2) and four days later (Time 3). RESULTS: Consistent with the diathesis-stress component of Beck's theory, dysfunctional attitudes predicted increases in depressed mood immediately following a negative admissions outcome (Time 2). In addition, consistent with the causal mediation component of the theory, in negative outcome students, the relationship between dysfunctional attitudes and increases in depressed mood was mediated by negative views of the future. Contrary to predictions, however, this relationship was not mediated by negative views of the self. In addition, contrary to predictions, dysfunctional attitudes did not predict enduring depressed mood after a negative outcome (Time 3). CONCLUSIONS: Individuals with dysfunctional attitudes are likely to show increases in depressed mood following the occurrence of negative events. The relationship between dysfunctional attitudes and increases in depressed mood following the occurrence of negative events is mediated by negative views of the future.

Adolescent↗

PubMed2004

Scattering properties of an impedance-matched, ideal, homogeneous, causal "left-handed" sphere.

The plane-wave scattering properties of a sphere of material having an ideal, homogeneous, and causal permittivity epsilon(f), and permeability mu(f) were investigated through detailed three-dimensional finite-difference time-domain, method-of-moments, and series-solution simulations. A Lorentzian functional form was chosen for epsilon(f) and mu( f), as it yields causal responses and allows us to study the physics of the left-handed-medium (LHM) regime. Our interest lies mainly in the frequency range where negative refraction [Re(n) < 0] is observed. We found that when operating in the LHM regime, an impedance-matched sphere responds with scattering features strikingly different from those found in ordinary materials. In particular, we found zero back-scattering and forward scattering that exceeds that of a metal sphere of similar size. The equality of E- and H-plane patterns was proved analytically and numerically, and the possibility of internal subwavelength focusing with a zero index sphere is also reported.

Journal Article↗

PubMed2024

The causal relationship between genetically predicted blood metabolites and idiopathic pulmonary fibrosis: A bidirectional two-sample Mendelian randomization study.

BACKGROUND: Numerous metabolomic studies have confirmed the pivotal role of metabolic abnormalities in the development of idiopathic pulmonary fibrosis (IPF). Nevertheless, there is a lack of evidence on the causal relationship between circulating metabolites and the risk of IPF. METHODS: The potential causality between 486 blood metabolites and IPF was determined through a bidirectional two-sample Mendelian randomization (TSMR) analysis. A genome-wide association study (GWAS) involving 7,824 participants was performed to analyze metabolite data, and a GWAS meta-analysis involving 6,257 IPF cases and 947,616 control European subjects was conducted to analyze IPF data. The TSMR analysis was performed primarily with the inverse variance weighted model, supplemented by weighted mode, MR-Egger regression, and weighted median estimators. A battery of sensitivity analyses was performed, including horizontal pleiotropy assessment, heterogeneity test, Steiger test, and leave-one-out analysis. Furthermore, replication analysis and meta-analysis were conducted with another GWAS dataset of IPF containing 4,125 IPF cases and 20,464 control subjects. Mediation analyses were used to identify the mediating role of confounders in the effect of metabolites on IPF. RESULTS: There were four metabolites associated with the elevated risk of IPF, namely glucose (odds ratio [OR] = 2.49, 95% confidence interval [95%CI] = 1.13-5.49, P = 0.024), urea (OR = 6.24, 95% CI = 1.77-22.02, P = 0.004), guanosine (OR = 1.57, 95%CI = 1.07-2.30, P = 0.021), and ADpSGEGDFXAEGGGVR (OR = 1.70, 95%CI = 1.00-2.88, P = 0.0496). Of note, the effect of guanosine on IPF was found to be mediated by gastroesophageal reflux disease. Reverse Mendelian randomization analysis displayed that IPF might slightly elevate guanosine levels in the blood. CONCLUSION: Conclusively, hyperglycemia may confer a promoting effect on IPF, highlighting that attention should be paid to the relationship between diabetes and IPF, not solely to the diagnosis of diabetes. Additionally, urea, guanosine, and ADpSGEGDFXAEGGGVR also facilitate the development of IPF. This study may provide a reference for analyzing the potential mechanism of IPF and carry implications for the prevention and treatment of IPF.

Humans↗

PubMed2005

Spatial navigation and causal analysis in a brain-based device modeling cortical-hippocampal interactions.

We describe Darwin X, a physical device that interacts with a real environment, whose behavior is guided by a simulated nervous system incorporating aspects of the detailed anatomy and physiology of the hippocampus and its surrounding regions. This brain-based device integrates cues from its environment and solves a spatial memory task. The responses of simulated neuronal units in the hippocampal areas during its exploratory behavior are comparable to place cells in the rodent hippocampus and emerged by associating sensory cues during exploration. To identify different functional hippocampal pathways and their influence on behavior, we employed a time series analysis that distinguishes causal interactions within and between simulated hippocampal and neocortical regions while the device is engaged in a spatial memory task. Our analysis identified different functional pathways within the neural simulation and prompts novel predictions about the influence of the perforant path, the trisynaptic loop and hippocampal-cortical interactions on place cell activity and behavior during navigation. Moreover, this causal time series analysis may be useful in analyzing networks in general.

Animals↗

PubMed1997

[Case report of two work accidents investigated using the causal tree method]

In a large company in São Paulo State, two work accidents were investigated using the Causal Tree Method (CTM), leading to the accurate identification of factors related to work organization as the causal factors for the accidents. These cases pointed to the role of organizational factors, such as improvised and temporary assignments to work stations and/or jobs, decisions about the performance of tasks left to unprepared workers, unavailability of proper tools and/or materials, and faulty information distribution within the company. Analysis of the accidents allowed for the presentation and discussion of the method (CTM), its lengthy application, its demands in terms of training, and its potentialities for accident prevention.

Journal Article↗

PubMed1998

A new causal model of dental diseases associated with endocarditis.

Infective endocarditis (IE) is a serious disease that is associated with dental diseases and treatment. The objective of this study was to summarize the epidemiological information about IE and reevaluate previous causal models in light of this evidence. The world biomedical literature was searched from 1930 to 1996 for descriptive and analytic epidemiological studies of IE. Multiple searching strategies were performed on 9 databases, including MEDLINE, CATLINE, and WORLDCAT. Results show that: 1) the incidence of IE varies between 0.70 to 6.8 per 100,000 person-years: 2) the incidence of IE increases 20 fold with advancing age: 3) over 50% of all IE cases are not associated with either an obvious procedural or infectious event 3 months prior to developing symptoms; 4) about 8% of all IE cases are associated with periodontal or dental disease without a dental procedure: 5) the time from the diagnosis of heart valve deformities to the development of IE approaches 20 years: 6) the median time from identifiable procedures to the onset of IE symptoms is about 2 to 4 weeks: 7) the risk of IE after a dental procedure is probably in the range of 1 per 3,000 to 5,000 procedures: and 8) over 80% of all IE cases are acquired in the community, and the bacteria are part of the host's endogenous flora. The synthesis of these data demonstrates that IE is a disorder with the epidemiological picture of a chronic disease such as cancer, instead of an acute infectious disease, with a long latent period and possibly several definable intermediates or stages. A new causal model is proposed that includes early bacteremias that may "prime" the endothelial surface of the heart valves over many years, and a late bacteremia over days to weeks that allows adherence and colonization of the valve, resulting in the characteristic fulminant infection.

Animals↗

PubMed2002

A new Poisson and Bayesian-based method to assign risk and causality in patients with suspected hepatic adverse drug reactions: a report of two new cases of ticlopidine-induced hepatotoxicity.

OBJECTIVE: The diagnosis of drug-induced hepatotoxicity is based on circumstantial evidence and is often inaccurate. We have designed a method based on published data to assign causality to suspected cases of drug-induced hepatotoxicity. DESIGN: Forty-seven published cases of ticlopidine-induced hepatotoxicity were identified by a Medline-based literature search. Data regarding abnormal liver function in patients receiving ticlopidine were obtained from the only published placebo-ticlopidine clinical trial (the Canadian American Ticlopidine Study; CATS). Thus, we calculated the maximum number of expected hepatotoxicity cases in patients exposed to ticlopidine and those not exposed to the drug by means of the Poisson distribution. The calculated odds ratio was used as a prior odd for subsequent quantification, using a Bayesian-based approach, of individual ticlopidine-induced hepatotoxicity likelihood. Concretely, the prior odd is modified by several separate likelihood ratios: age; sex; AST level; ALT level; alkaline phosphatase level; total bilirubin level; latent period of adverse reaction appearance; and period of remission of adverse reaction. This methodology was applied to two new cases of suspected ticlopidine-induced hepatotoxicity. RESULTS: The prior probability of ticlopidine-induced hepatotoxicity derived from CATS data is 61.29%. This is in contrast with the 28.83% incidence rate of drug-induced liver alterations in the general population. Alkaline phosphatase levels and total bilirubin levels were six times the normal values among individuals with ticlopidine-induced hepatotoxicity than in the general population. They were the most relevant likelihood ratios of the Bayesian model to establish a high level of causality relationship between a hepatotoxicity event and ticlopidine use. CONCLUSIONS: The proposed method, which links information from clinical trials with the profile of clinical hepatotoxicity of a drug defined from published cases reported after a drug is marketed, can be a useful tool for drug postmarketing surveillance research.

Adult↗

PubMed2026

Shared Genetic Basis, Biological Function and Causal Relationship Between Sleep Traits and Hypothyroidism: Evidence from a Comprehensive Genetic Analysis.

BACKGROUND: This research attempts to clarify whether there are any genetic similarities between sleep traits and hypothyroidism based on publicly accessible large-scale genomewide association studies. METHODS: The methodology included colocalization analysis, cross-phenotype association analysis, and linkage disequilibrium score regression analysis to find common genetic overlap. Through tissue function specificity and functional mapping, we were able to identify the shared genetic level. Genetic instrumental factors were used for causal inference in two-sample univariate and multivariable Mendelian randomization analyses. RESULTS: A hereditary correlation between hypothyroidism and napping during the day and getting up in the morning (rg= -0.0982, P= 0.0007; rg= -0.101, P= 0.0001). MAGI3, and HLA-DRB1 BX296568.1 may be potential targets for shared treatments. Colocalization and tissue-specific analysis demonstrated that the common genes and SNPs were identified in the thyroid, lung, brain, and lymphatic tissues. Functional analysis emphasized the importance of these common genes in processes like as protein transport, inflammatory response, and MHC class II protein synthesis. Furthermore, an association has been established between hypothyroidism and sleep duration (IVW, OR 1.5208; 95% CI 1.1142-2.0758, P=0.0082) and getting up in the morning (IVW, OR 1.8375; 95%CI: 1.4502-2.3284, P=4.73E-07). Furthermore, the reverse MR analysis revealed no causal connection between aberrant sleep traits and hypothyroidism. The enduring impact of insomnia on hypothyroidism persists despite controlling for alcohol consumption and smoking habits. CONCLUSION: Certain genetic correlations between sleep traits and hypothyroidism have been emphasized. These findings may elucidate the origin of comorbidity and have implications for future clinical trials.

Humans↗

PubMed1999

Peer cluster theory and adolescent alcohol use: an explanation of alcohol use and a comparative analysis between two causal models.

This study tests the premise of peer cluster theory as it applies to individual alcohol use, and makes a comparative analysis between its ability to explain alcohol use and marijuana use. Using the results of a 1996 drug and alcohol survey of 1312 Western Kentucky University students, path analysis was used to measure the influence of six of peer cluster theory's psychosocial characteristics on the percentage of the respondent's college friends who use alcohol. All of these variables were then regressed on the respondent's alcohol use. The results of the causal models did show some support for peer cluster theory. The direct effect of the student's association with alcohol-using peers on individual alcohol use was shown to have the strongest direct influence on this outcome variable. However, a few limitations of this theoretical perspective were identified. The causal model for alcohol use showed that the indirect influence of two of these psychosocial characteristics (parental attitudes on alcohol use and success in school) was weaker than their direct influence on individual alcohol use. And, the comparative analysis showed that peer cluster theory is better suited to explain the use of marijuana than the use of alcohol.

Adolescent↗