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Results for “External validity”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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At least 1,513 records · Page 84Linked to original sources
PubMed1993

Evaluating the computer as a data camera in family planning research.

"This chapter explores both the potential and limitations of the micro-computer as a research tool for unobtrusive data collection in the area of population and family planning.... To provide concrete examples of the computer's potential usefulness as well as its limitations, two research projects undertaken [in the United States] by the author and colleagues will be discussed.... Each program offers different applications of how the computer can be used to: (1) evaluate programs; (2) collect descriptive data about users' values, decisions, and previous behaviors regarding sexual issues, and (3) develop and test cognitive and behavior models. Each application also offers examples of the limitations of the computer in terms of external validity issues (i.e., how representative are samples of persons who use the computer voluntarily), the need to check the validity of responses typed by computer users, and ethical issues involved in using the computer to collect data."

Americas↗
PubMedDate not supplied

[Randomized controlled trials: a controversial past and a future of regulation and rejection].

The quality of randomized controlled clinical trials has a pivotal role in their external validity. There are no definite protocols to evaluate the quality of already published studies, whereas international guidelines for the preparation of randomized controlled trials are available. This review outlines some milestones in the development of guidelines for randomized controlled trials and presents the Revised Consort Statement which includes 22 items, sub divided into sections (title and abstract, introduction, methods, results and discussion) and a flow chart. The aim of this analysis is to provide clinical researchers with a valuable working tool. Finally, future guidelines for systematic reviews of randomized controlled studies are presented according to the Cochrane Collaboration model.

Double-Blind Method↗
PubMed2002

Social science research and experimentation in Australian criminal proceedings: prejudicial pre-trial publicity and psychological research.

Using the decision of Barr J in Attorney-General (NSW) v John Fairfax Publications [1999] NSWSC 318, the authors analyse the need for external validity and relevance in social science evidence adduced in the courts. They argue in favour of the rigour employed within Barr J's judgment and contend that a constructive legacy of the decision should be a greater sensitisation on the part of researchers to the kinds of factors that can distance experimental scenarios from curial contexts to a point where generalisations from the former become strained and even spurious. A number of these considerations have the potential to be addressed to a significant extent by improved methodologies. However, the authors warn against an excess of purist fervour in demanding complete comparability of scenarios, lest the fruits of social science be denied to the courts and decision-making be adversely affected by the absence of expert insights falling short of complete replication of conditions between experiments and forensic reality.

Australia↗
PubMed2002

Assessment in dental VT... can we do better?

During the VT year the VDP and the trainer could choose to progressively check and complete each of the competencies listed and using the skills evaluation document make the appropriate record. Any areas of further training needs would be identified and a learning plan implemented. The whole process would be supervised by the VT advisor group who could be the resource for further training or support in conjunction with the VDP and trainer. This would be a self evaluation with external validation by the trainer and advisor group similar to the AEGD model in the USA. This would be an assessment that was valid, reliable and feasible as identified by Freeman. The use of a skills evaluation procedure would be similar to a LEP which would support the validity of the process. A record of completion of each key skill (competency) could be made using the supplied paper work and presented periodically as a log of achievement to the VT Advisor group. Of course the whole process also relies on the fact that the trainers need to be competent themselves in using practice based assessment, and an appropriately resourced pilot programme will be needed to make this an effective tool in assessing the overall competency of new graduates in vocational training.

Competency-Based Education↗
PubMed2001

Evaluation of Selected Behavior Change Theoretical Models Used in Weight Management Interventions.

Purpose: This paper evaluates selected behavior change theoretical models used in weight reduction interventions and presents recommendations for the use of theory in weight reduction research. Overweight and obesity are complex problems, requiring long-term behavioral change. Behavioral treatments for overweight and obesity are as varied as the elements of behavior, and the long-term efficacy of most approaches is poor. Because of the complexity of both the problem and its treatment, investigations must target the development of cause-effect explanations. CONCLUSIONS: Many of the behavioral change intervention studies reviewed lacked external validity, primarily due to the failure to consider salient moderators. The theoretical models reviewed in this paper were primarily tested on white, employed populations. These and other data suggest that extant theoretical approaches may not be salient in certain groups. IMPLICATIONS: Practice implications include: 1) assess indicators for readiness to engage in weight reduction efforts; 2) base interventions on multiple theories; and 3) develop context-based interventions. Future research should include a focus on innovative methods in theory development, development of theory acknowledging mediator/moderator interactions, development of theory in context, and development of theory reflecting cultural meaning and diversity.

Journal Article↗
PubMed2000

[Efficiency of ultrasonography in the diagnosis of acute appendicitis].

UNLABELLED: Importance of the problem. Atypical or precocious presentation of acute appendicitis in children causes false diagnosis. OBJECTIVES: To determine internal and external validity of ultrasonography for confirmation diagnosis of acute appendicitis. PATIENTS AND METHODS: Patients with suspicious acute appendicitis treated in 1998. They have been classified into two groups. Group 1: patients with appendicitis; Group 2: patients with non-specific abdominal pain. MATERIAL: Ultrasonography equipment (5 and 7.5 MHz). METHOD: Ultrasonography has been considered as positive when 3 or more of the typical signs of appendicitis have been detected. Analysis unit: positivity of the test and presence or absence of illness confirmed by histologic analysis of the appendix obtained through laparotomy. RESULTS: Number of patients selected for the work: 139. Middle age: 8 years-old (range: 2 to 14 years); 75% were males, 25% females. Patients included in group 1: 42; patients included in group 2:97. False positive rate was 12.23%, while false negative rate was 7.19%. Sensibility was 76%, specificity was 82%, positive predictive value was 65%, negative predictive value was 88% and precision was 80%. Odds-ratio pre-test: 0.43; Odds-ratio post-test: 0.64. CONCLUSIONS: Probability of accuracy diagnosis is duplicated by ultrasonography. Liability of the test is diminished by variability due to observer.

Acute Disease↗
PubMed2003

[Economic assessment, a field between clinical research and observational studies].

Health technology assessments propose to study the differential impact of health interventions in a complex care system which is characterised by the multitude of individual behaviours and the diverse nature of the institutions involved. Current systems for data collection lend themselves poorly to this rigorous analysis of efficacy of treatments in the actual situations where they are used. Randomised trials endeavour to neutralise any parasitic interference which could compromise testing for a causal relationship between the treatment administered and the result obtained. Their methodology which establishes the term ceteris paribus in the principle of good practice lends itself poorly to an analysis of individual behaviour. Observational studies are start from actual treatment situations to describe them as reliably as possible. By definition, however, these assume that the natural course of events is not deviated by any intervention. The absence of an experimental plan increases the likelihood of bias and makes it more difficult to test for causal relationships. They lend themselves poorly to testing for incremental efficacy. The two instruments to be preferred are decisional analysis and quasi-experimental studies. Decisional analysis help to avoid the problems of external validity associated with randomised clinical trials by associating parameters which are extracted from data obtained from everyday practice. Quasi-experimental studies or pragmatic trials are based on the reality of behaviour of the prescriber and his/her patients; their impact on efficacy, quality of life social costs of the disease and of treatments may be identified under normal conditions of use.

Biomedical Research↗
PubMed1999

Finding the truth: a guide to interpreting HIV clinical trials.

The complex social, epidemiologic, and pathologic aspects of HIV disease, the variation in the nature of the disease from person to person, and the constantly changing roster of available treatments create intense and often contradictory concerns. Clinical trials are rarely interested only in the study patients, but are designed to enable us to make inferences about a general HIV-infected population. To do this most effectively, we must confirm the internal and external validity of the study. Statistics enable us to generalize from a particular study to the broader population, but the statistical problems arising from AIDS clinical trials are unique and complex.

Bias↗
PubMed1999

Managing cognitive impairment in the elderly: conceptual, intervention and methodological issues.

PURPOSE: With the aging of society, the incidence of dementia in the elderly is also increasing, and thus results in increased numbers of individuals with cognitive impairment. Nurses and other researchers have investigated issues concerning the management of cognitive impairment. This article highlights conceptual, intervention and methodological issues associated with this phenomenon. CONCLUSIONS: Cognitive change is a multivariate construct that includes alterations in a variety of information processing mechanisms such as problem solving ability, memory, perception, attention and learning, and judgement. Although there is a large body of research, conceptual, intervention and methodological issues remain. Much of the clinical research on cognitive impairment is atheoretical, with this issue only recently being addressed. While many clinical interventions have been proposed, few have been adequately tested. There are also various methodological concerns, such as small sample sizes and limited statistical power; study design issues (experimental vs. non-experimental), and internal and external validity problems. Clearly, additional research designed to intervene with these difficult behaviors is needed. IMPLICATIONS: A variety of psychosocial, environmental and physical parameters must be considered in the nursing care of persons with cognitive impairment. Special attention has been given to interventions associated with disruptive behaviors. Interventions are complex and knowledge must be integrated from both the biomedical and behavioral sciences in order to deal effectively with the numerous problems that can arise over a long and changing clinical course. Some researchers and clinicians have suggested that a new culture regarding dementia care is needed, one that focuses on changing attitudes and beliefs about persons with dementia and one that changes how organizations deliver that care. This review identifies key conceptual, intervention and methodological issues and recommends how these issues might be addressed in the future.

Journal Article↗
PubMed2003

[A new measure. New studies require new criteria for critical appraisal].

Over the last ten years the quality of published clinical trials has improved considerably. Randomised controlled design, concealed allocation, blinding, clinically relevant outcomes, large sample sizes and almost complete follow-up are standard features of most trials. As a result, standard evidence-based medicine criteria can no longer be used to separate the "wheat from the chaff". Here, we discuss recent studies which reveal only marginal superiority of new treatments over well-established and effective therapies. Nowadays, readers of reports should be particularly aware of the definition of control therapies, of clinical relevance when results are statistically significant, of the external validity and whether a trial serves a pragmatic or explanatory purpose.

Clinical Trials as Topic↗
PubMed2003

[Critical appraisal of the literature in systematic review].

Critical appraisal of a literature is an important part of Systematic Review(SR) of laboratory tests. In this process, the quality of the clinical study is evaluated by using knowledge of clinical epidemiology and biostatistics. In the critical appraisal of articles of diagnostic tests, estimation of the design related bias, such as selection bias, spectrum bias, work-up bias, and referral bias, is extremely important. This article introduces the checklist for a diagnostic test proposed by the EBD collaboration in Japan. The proposed checklist consists of 23 items which effect on quality and external validity of the clinical studies. It will become a useful tool for systematic review in laboratory medicine.

Clinical Laboratory Techniques↗
PubMed1987

Utility of cluster analysis in classification of mixed neuropsychiatric patients.

This study examines the hypothesis that reliable neuropsychologically-based subgroups can be found in a mixed neuropsychiatric patient sample (N = 600) and that the subtype membership will be associated with external diagnostic and case history variables. A modified Halstead-Reitan Neuropsychological Test Battery was employed. The sample was randomly divided into two groups of 300 each. Results show three reliable cluster analytically-based groups that differ as a function of level, but not pattern of performance. External validation failed to show the cluster groups to be significantly related to any of the neurodiagnostic or case history variables, except that the severely impaired group had a greater preponderance of organic diagnoses and a longer history of hospitalisation. Caution is warranted in using configural analysis of standard neuropsychological test batteries in an effort to identify subtypes in a mixed neuropsychiatric patient population.

Journal Article↗
PubMed1997

Modal profiles for the Halstead-Reitan Neuropsychological Battery for Children.

Modal Profile Analysis was used to cluster students (aged 9 to 14 years) on 16 subtest scores from the Halstead-Reitan Neuropsychological Battery for Children (HRNB-C). This analysis produced eight modal profile types, all of which were replicated in multiple samples. An initial attempt to establish external validity indicated that the modal groups display dissimilar patterns of performance on independent variables. The present typology is compared to similar typologies developed with adult neuropsychological data. In sum, the current classification system provided less coverage than the adult typologies, but produced more unique or homogeneous modal groups. Discussion focuses on potential clinical and research uses of the modal HRNB-C profiles.

Journal Article↗
PubMed2003

Using discrete choice experiments to value health care programmes: current practice and future research reflections.

There has been growing interest in discrete choice experiments (DCEs) in health economics over the last few years. This paper identifies and describes applications conducted during 1990-2000. From this basis some important areas for future research are reflected upon. These include: having a better understanding of how respondents interpret price, risk and time attributes; strengthening designs and analysis; investigating decision making heuristics employed when completing DCEs, and the extent these are related to the complexity of the task; external validity, reliability and generalisability. Collaborative work with statistical design experts, psychologists, sociologists and qualitative researchers will prove useful when investigating these issues. It is also critical to link, more generally, the research agenda to work being carried out in marketing, transport and environmental economics and health economics benefit assessment.

Attitude to Health↗
PubMed2004

Head injury and the ability to feign neuropsychological deficits.

This study investigated the possibility that head-injured patients, by virtue of their exposure to medical and legal evaluations, are better able to feign deficits than controls. Both internal and external validity issues were addressed in a malingering simulation using 46 moderately to severely head injured and 46 matched control subjects who were administered a battery of neuropsychological and motivational tests under standard or malingering instructions. Results showed no significant interaction between malingering instructions and head injury status on commonly used motivational tests or neuropsychological tests, nor were the head injured malingerers better able to avoid detection using established cutting scores on motivational tests. These results suggest that head injured individuals are no more able to feign neuropsychological deficits successfully than non-head injured individuals.

Case-Control Studies↗
PubMedDate not supplied

[Neuropsychological Assessment of Children: a test battery for children between 5 and 16 years of age. A Colombian normative study].

INTRODUCTION: A neuropsychological test battery for 5 to 16 year old children has recently been developed. This battery is called Neuropsychological Assessment of Children (Evaluacion Neuropsicológica Infantil, ENI) and it includes the following sections: attention, constructional skills, memory encoding, perceptual skills, memory recall, language, metalinguistic skills, reading, writing, arithmetic, spatial skills, conceptual skills and executive functions. AIMS: Our aim was to obtain norms for the ENI in a Colombian population between 5 and 16 years of age. SUBJECTS AND METHODS: We selected 252 children (92 boys and 160 girls) in the city of Manizales (Colombia), and they were administered the ENI. In order to obtain an external validity, 21 of the participants were also given the Wechsler Intelligence Scale for Children Revised (WISC R). RESULTS: Statistically significant differences were found on most of the subtests across age groups. Differences between boys and girls appeared more specifically in tests of visuoperceptual, visual constructional, spatial and numerical skills. Some of the ENI subtests correlated with the WISC R subtests. CONCLUSIONS: It is suggested that the ENI could satisfy the existing need in the Spanish speaking world for neuropsychological tools with which to assess children and adolescents.

Adolescent↗
PubMed2004

[Psychotherapy and evidence-based medicine (EBM)--randomized controlled vs. naturalistic studies: is there only one gold standard?].

OBJECTIVES: The present article deals with the question as to which kind of evidence is necessary to demonstrate the effectiveness of a psychotherapeutic method. RESULTS: The authors point out that randomized controlled studies (RCTs) are carried out in standardized laboratory contexts, whereas naturalistic studies are based on conditions in the psychotherapeutic practice. Accordingly, RCTs and naturalistic studies address different questions of research (laboratory vs. field). CONCLUSIONS: This view has several important implications: (1.) RCTs and naturalistic studies do not differ concerning their internal and external validity. (2.) In principal, naturalistic studies do not provide lower level evidence than RCTs. (3.) Evidence from RCTs cannot be transferred to psychotherapeutic practice in the field: If a therapy has worked in an RCT, this does not necessarily imply that it will work in the field as well. (4.) Naturalistic studies provide important evidence for determining the effectiveness of a therapy in practice. (5.) The proposed catalogues for levels of evidence focus on RCTs. Thus, they cannot be applied to hypotheses on the effectiveness of a therapy in the field (naturalistic studies). (6.) It is necessary to define separate criteria for levels of evidence of naturalistic studies. In this article, criteria and levels of evidence of naturalistic studies are defined. The implications of the differentiation of randomized controlled vs. naturalistic studies is discussed.

Evidence-Based Medicine↗
PubMed2004

Are we missing anything? Pursuing research on attrition.

Attrition, or loss of participants over the course of a study, presents a significant threat to the integrity of a longitudinal research study and theory development resulting from the study. Although there has been a recent resurgence of interest in attrition, it is an underreported and understudied phenomenon despite its potential to introduce bias. Internal and external validity, reliability, and statistical validity are all impacted by a small sample and, most likely, a non-randomness in the study sample. Development of a theory of attrition will assist researchers in development of sampling strategies that will enhance the quality of their data in longitudinal designs. An ecological theoretical model of research participation is proposed and described.

Bias↗