What conclusions should we draw from the data?

1995 ◽  
Vol 84 (02) ◽  
pp. 95-101 ◽  
Author(s):  
Andrew Vickers
Keyword(s):  
Cohort Studies ◽  
External Validity ◽  
Large Scale ◽  
Critical Appraisal ◽  
Internal Validity ◽  
Research Process ◽  
Clinical Value ◽  
Blind Trials

AbstractCritical appraisal of a scientific trial involves deciding on its internal validity— whether the hypothesis has been correctly accepted or rejected—and its external validity—the extent to which the trial's findings can be generalized. Discourse on homoeopathic research has focused on the former at the expense of the latter and an analysis of homoeopathic research demonstrates that it has low external validity. One solution would be to split the research process in two. Large scale, triple-blind trials could be used to determine the extent to which the action of homoeopathy may be explained by placebo. Importantly, no assessment of external validity would be made. Audit and cohort studies could then be used to examine questions usually associated with external validity, such as the conditions most suitable for treatment and the long-term clinical value of homoeopathy.

Critical Appraisal of Epidemiological Studies and Clinical Trials

2017 ◽  
Author(s):  
Mark Elwood
Keyword(s):  
Cohort Studies ◽  
Statistical Methods ◽  
Critical Appraisal ◽  
Causal Effect ◽  
Internal Validity ◽  
Epidemiological Studies ◽  
Case Control ◽  
Randomised Trials ◽  
Case Control Studies ◽  
Retrospective Cohort Studies

This book presents a system of critical appraisal applicable to clinical, epidemiological and public health studies and to many other fields. It assumes no prior knowledge. The methods are relevant to students, practitioners and policymakers. The book shows how to assess if the results of one study or of many studies show a causal effect. The book discusses study designs: randomised and non-randomised trials, cohort studies, case-control studies, and surveys, showing the presentation of results including person-time and survival analysis, and issues in the selection of subjects. The system shows how to describe a study, how to detect and assess selection biases, observation bias, confounding, and chance variation, and how to assess internal validity and external validity (generalisability). Statistical methods are presented assuming no previous knowledge, and showing applications to each study design. Positive features of causation including strength, dose-response, and consistency are discussed. The book shows how to do systematic reviews and meta-analyses, and discusses publication bias. Systems of assessing all evidence are shown, leading to a general method of critical appraisal based on 20 key questions in five groups, which can be applied to any type of study or any topic. Six chapters show the application of this method to randomised trials, prospective and retrospective cohort studies, and case-control studies. An appendix summarises key statistical methods, each with a worked example. Each main chapter has self-test questions, with answers provided.

scholarly journals Large-scale evidence generation and evaluation across a network of databases (LEGEND): assessing validity using hypertension as a case study

2020 ◽  
Vol 27 (8) ◽  
pp. 1268-1277 ◽  
Author(s):  
Martijn J Schuemie ◽  
Patrick B Ryan ◽  
Nicole Pratt ◽  
RuiJun Chen ◽  
Seng Chan You ◽  
...  
Keyword(s):  
Propensity Score ◽  
Confidence Intervals ◽  
External Validity ◽  
Large Scale ◽  
Internal Validity ◽  
Medical Decision ◽  
Observational Research ◽  
High Quality ◽  
Meta Analyses ◽  
Evidence Generation

Abstract Objectives To demonstrate the application of the Large-scale Evidence Generation and Evaluation across a Network of Databases (LEGEND) principles described in our companion article to hypertension treatments and assess internal and external validity of the generated evidence. Materials and Methods LEGEND defines a process for high-quality observational research based on 10 guiding principles. We demonstrate how this process, here implemented through large-scale propensity score modeling, negative and positive control questions, empirical calibration, and full transparency, can be applied to compare antihypertensive drug therapies. We assess internal validity through covariate balance, confidence-interval coverage, between-database heterogeneity, and transitivity of results. We assess external validity through comparison to direct meta-analyses of randomized controlled trials (RCTs). Results From 21.6 million unique antihypertensive new users, we generate 6 076 775 effect size estimates for 699 872 research questions on 12 946 treatment comparisons. Through propensity score matching, we achieve balance on all baseline patient characteristics for 75% of estimates, observe 95.7% coverage in our effect-estimate 95% confidence intervals, find high between-database consistency, and achieve transitivity in 84.8% of triplet hypotheses. Compared with meta-analyses of RCTs, our results are consistent with 28 of 30 comparisons while providing narrower confidence intervals. Conclusion We find that these LEGEND results show high internal validity and are congruent with meta-analyses of RCTs. For these reasons we believe that evidence generated by LEGEND is of high quality and can inform medical decision-making where evidence is currently lacking. Subsequent publications will explore the clinical interpretations of this evidence.

Quality of life measurements in major depression

1996 ◽  
Vol 11 (3) ◽  
pp. 123-126 ◽  
Author(s):  
P Bech
Keyword(s):  
Quality Of Life ◽  
Clinical Trials ◽  
Major Depression ◽  
External Validity ◽  
Randomized Clinical Trials ◽  
Internal Validity ◽  
Efficacy And Safety ◽  
Quality Of Life Measurements

SummaryIn randomized clinical trials in patients with major depression quality of life is considered as an important dimension of treatment outcome in relation to clinical efficacy and safety. The internal validity, reliability, as well as external validity of quality of life scales have been analysed. It is concluded that such scales have their most appropriate applicability in medicine and long-term trials with antidepressants.

scholarly journals IMPACT OF SOCIAL DISTANCING IN CURBING COVID-19 PANDEMIC: A SYSTEMATIC REVIEW

2021 ◽  
Vol 8 (3) ◽  
pp. 165-172
Author(s):  
M. Ammar Luthfi Kurniawan ◽  
Litania Leona Hidayat ◽  
Jihan Natra Shafira ◽  
Iche Andriyani Liberty
Keyword(s):  
Systematic Review ◽  
Large Scale ◽  
Critical Appraisal ◽  
Behavioral Adjustment ◽  
Contact Tracing ◽  
Social Distancing ◽  
Electronic Search ◽  
Large Scale Testing ◽  
The Impact

Social distancing includes strategies to ban public gatherings and advise individuals to stay at their home or maintain distance to one another by at least 1-2 meters. This study aims to intend to assess all the available evidence of social distancing in decreasing COVID-19 transmission in the general population. We conducted an electronic search of published literature using MEDLINE/Pubmed, Science direct, PMC, Wiley, and Google Scholar and we use Joanna Briggs Institute (JBI) critical appraisal checklist to assess methodological qualities. A total of 7 articles were decided to be included in this study. Social distancing has curb down the number and saved approximately 10 thousand Brazilian lives. A study by VoPham et al on the association of social distancing and COVID-19 incidence found higher social distancing was associated with a 29% reduction of COVID-19 incidence (adjusted IRR 0.71;95% CI (0,57-0,87) and 35% reduction of COVID-19 mortality (adjusted IRR 0,65; 95% CI 0,55-0,76). Social distancing is one of the major policies implemented for long-term behavioral adjustment in managing the COVID-19 pandemic. Passive social distancing is not enough to drag down the number, there needs to be large scale testing, isolation, and contact tracing. However, we believe we have illuminated the impact of social distancing on the COVID-19 pandemic and add to the available literature the basis of social distancing in reducing transmission of COVID-19.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

Computer Analyses in Preventive Health Research

1967 ◽  
Vol 06 (01) ◽  
pp. 8-14 ◽  
Author(s):  
M. F. Collen
Keyword(s):  
Medical Research ◽  
Preventive Medicine ◽  
Health Research ◽  
Large Scale ◽  
Preventive Health ◽  
New Era ◽  
Large Numbers ◽  
Normal Test ◽  
Computer Analyses

The utilization of an automated multitest laboratory as a data acquisition center and of a computer for trie data processing and analysis permits large scale preventive medical research previously not feasible. Normal test values are easily generated for the particular population studied. Long-term epidemiological research on large numbers of persons becomes practical. It is our belief that the advent of automation and computers has introduced a new era of preventive medicine.

Evidence-Based Social Sciences: A New Emerging Field

2018 ◽  
Vol 5 (2) ◽  
pp. 207-211
Author(s):  
Nazila Zarghi ◽  
Soheil Dastmalchian Khorasani
Keyword(s):  
Social Sciences ◽  
Critical Appraisal ◽  
State Of The Art ◽  
Internal Validity ◽  
Evidence Based ◽  
Multiple Sources ◽  
Social Settings ◽  
Research Findings ◽  
Academic Area ◽  
Different Levels

Abstract Evidence based social sciences, is one of the state-of- the-art area in this field. It is making decisions on the basis of conscientious, explicit and judicious use of the best available evidence from multiple sources. It also could be conducive to evidence based social work, i.e a kind of evidence based practice in some extent. In this new emerging field, the research findings help social workers in different levels of social sciences such as policy making, management, academic area, education, and social settings, etc.When using research in real setting, it is necessary to do critical appraisal, not only for trustingon internal validity or rigor methodology of the paper, but also for knowing in what extent research findings could be applied in real setting. Undoubtedly, the latter it is a kind of subjective judgment. As social sciences findings are highly context bound, it is necessary to pay more attention to this area. The present paper tries to introduce firstly evidence based social sciences and its importance and then propose criteria for critical appraisal of research findings for application in society.

(A review) Atlas of especially protected natural areas of Saint Petersburg / Ed. in chief V. N. Khramtsov, T. V. Kovaleva, N. Yu. Natsvaladze. St. Petersburg, 2013. 176 p.

2014 ◽  
pp. 124-129
Author(s):  
Z. V. Karamysheva
Keyword(s):  
Protected Areas ◽  
Large Scale ◽  
Natural Areas ◽  
Natural Protected Areas ◽  
Saint Petersburg ◽  
Natural Processes ◽  
Original Illustrations ◽  
Vegetation Maps ◽  
Protected Natural Areas

The review contains detailed description of the «Atlas of especially protected natural areas of Saint Petersburg» published in 2013. This publication presents the results of long-term studies of 12 natural protected areas made by a large research team in the years from 2002 to 2013 (see References). The Atlas contains a large number of the historical maps, new satellite images, the original illustrations, detailed texts on the nature of protected areas, summary tables of rare species of vascular plants, fungi and vertebrates recorded in these areas. Special attention is paid to the principles of thematic large-scale mapping. The landscape maps, the vegetation maps as well as the maps of natural processes in landscapes are included. Reviewed Atlas deserves the highest praise.

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