Because negative findings have less chance of getting published, available studies tend to be a biased sample. This leads to an inflation of effect size estimates to an unknown degree. To see how meta-analyses in education account for publication bias, we surveyed all meta-analyses published in the last five years in the Review of Educational Research and Educational Research Review. The results show that meta-analyses usually neglect publication bias adjustment. In the minority of meta-analyses adjusting for bias, mostly non-principled adjustment methods were used, and only rarely were the conclusions based on corrected estimates, rendering the adjustment inconsequential. It is argued that appropriate state-of-the-art adjustment (e.g., selection models) should be attempted by default, yet one needs to take into account the uncertainty inherent in any meta-analytic inference under bias. We conclude by providing practical recommendations on dealing with publication bias.
- MeSH
- biomedicínský výzkum * MeSH
- lidé MeSH
- metaanalýza jako téma * MeSH
- publikační zkreslení * MeSH
- žurnalistika lékařská (masmédia) MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Currently, the deployment of tracking devices is one of the most frequently used approaches to study movement ecology of birds. Recent miniaturization of light-level geolocators enabled studying small bird species whose migratory patterns were widely unknown. However, geolocators may reduce vital rates in tagged birds and may bias obtained movement data. There is a need for a thorough assessment of the potential tag effects on small birds, as previous meta-analyses did not evaluate unpublished data and impact of multiple life-history traits, focused mainly on large species and the number of published studies tagging small birds has increased substantially. We quantitatively reviewed 549 records extracted from 74 published and 48 unpublished studies on over 7,800 tagged and 17,800 control individuals to examine the effects of geolocator tagging on small bird species (body mass <100 g). We calculated the effect of tagging on apparent survival, condition, phenology and breeding performance and identified the most important predictors of the magnitude of effect sizes. Even though the effects were not statistically significant in phylogenetically controlled models, we found a weak negative impact of geolocators on apparent survival. The negative effect on apparent survival was stronger with increasing relative load of the device and with geolocators attached using elastic harnesses. Moreover, tagging effects were stronger in smaller species. In conclusion, we found a weak effect on apparent survival of tagged birds and managed to pinpoint key aspects and drivers of tagging effects. We provide recommendations for establishing matched control group for proper effect size assessment in future studies and outline various aspects of tagging that need further investigation. Finally, our results encourage further use of geolocators on small bird species but the ethical aspects and scientific benefits should always be considered.
- MeSH
- fylogeneze MeSH
- migrace zvířat * MeSH
- ptáci * MeSH
- publikační zkreslení MeSH
- roční období MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- metaanalýza MeSH
- práce podpořená grantem MeSH
Background: The World Medical Association's Declaration of Helsinki explicitely requires registration of a study involving human subjects before its onset. The registration creates an opportunity for improvement of design and avoidance of bias. Objective: The aim of this article was to elaborate a need for creating regional registry of clinical studies for Balkan countries. Methods: Available international, national and regional registries were searched for in PUBMED database and by general purpose search engines like Google or Yahoo. The following types of publications were included in the survey: original studies, case studies, case reports, narrative reviews, commentaries and expert opinions. Results. The most important international registries of research involving human subjects are „ClinicalTrials.gov“ dabase of US National Institute of Health, the World Health Organization's „International Clinical Trials Registry Platform“, PROSPERO and Cochrane Database of Systematic reviews and meta-analyses, and the Research Registry, focusing on observational studies. National registries were established in Japan, South Korea, Sri Lanka, China, and others countries, while European Union has the most elaborate of regional registries. National and regional registries performe better than large international ones: the registrations are more complete, and researchers are more aware of their obigation to pre-register a clinical study. Conclusions. There is great need for one regional registry of clinical studies for Balkan countries, which would suit well the whole region, considering great socio-economic, cultural and lingual similarities of the Balkan countries.
- MeSH
- biomedicínský výzkum MeSH
- klinická studie jako téma MeSH
- lidé MeSH
- předběžná registrace publikace * MeSH
- publikační zkreslení MeSH
- publikování etika MeSH
- vědecká komunikace etika MeSH
- Check Tag
- lidé MeSH
- Geografické názvy
- Balkánský poloostrov MeSH
BACKGROUND: CpG Island Methylator Phenotype (CIMP) is an epigenetic phenotype in CRC characterized by hypermethylation of CpG islands in promoter regions of tumor suppressor genes, leading to their transcriptional silencing and loss of function. While the prevalence of CRC differs across geographical regions, no studies have compared prevalence of CIMP-High phenotype across regions. The purpose of this project was to compare the prevalence of CIMP across geographical regions after adjusting for variations in methodologies to measure CIMP in a meta-analysis. METHODS: We searched PubMed, Medline, and Embase for articles focusing on CIMP published from 2000 to 2018. Two reviewers independently identified 111 articles to be included in final meta-analysis. We classified methods used to quantify CIMP into 4 categories: a) Classical (MINT marker) Panel group b) Weisenberg-Ogino (W-O) group c) Human Methylation Arrays group and d) Miscellaneous group. We compared the prevalence of CIMP across geographical regions after correcting for methodological variations using meta-regression techniques. RESULTS: The pooled prevalence of CIMP-High across all studies was 22% (95% confidence interval:21-24%; I2 = 94.75%). Pooled prevalence of CIMP-H across Asia, Australia, Europe, North America and South America was 22, 21, 21, 27 and 25%, respectively. Meta-regression analysis identified no significant differences in the prevalence of CIMP-H across geographical regions after correction for methodological variations. In exploratory analysis, we observed variations in CIMP-H prevalence across countries. CONCLUSION: Although no differences were found for CIMP-H prevalence across countries, further studies are needed to compare the influence of demographic, lifestyle and environmental factors in relation to the prevalence of CIMP across geographical regions.
- MeSH
- CpG ostrůvky genetika MeSH
- fenotyp * MeSH
- genetická heterogenita MeSH
- kohortové studie MeSH
- kolorektální nádory genetika MeSH
- lidé MeSH
- metylace DNA genetika MeSH
- pití alkoholu škodlivé účinky genetika MeSH
- prevalence MeSH
- promotorové oblasti (genetika) genetika MeSH
- publikační zkreslení MeSH
- rizikové faktory MeSH
- umlčování genů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- metaanalýza MeSH
- systematický přehled MeSH
- Geografické názvy
- Česká republika MeSH
- Indie MeSH
- MeSH
- autistická porucha MeSH
- lidé MeSH
- odmítnutí terapie pacientem MeSH
- postoj MeSH
- publikační zkreslení MeSH
- vakcinace * etika MeSH
- výzkum MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- novinové články MeSH
Performance evaluation of scientific work on regional and individual levels can be achieved by the using scientometric methods of a quantitative analysis of bibliographic information available in such databases as Science Citation Index (SCI). Unfortunately, Kazakhstan scientific journals have not been included yet in the Thomson Reuters Corp. register of periodicals, that substantially distorts the actual national scientometric indexes. The analysis of Database “National Citation Reports” (Kazakhstan), which correlated with a contribution of Kazakhstan into the world science development, has shown the low level of research activities of Kazakhstan scientists on international arena. So, the share of international publications of Kazakhstan in the global flow is equal to 0,021 % (1044 doc.) that corresponds to the 87th place in the general list of countries of 177 names. Subject to the ranking of countries into groups by the number of the published works, Kazakhstan is referring to the group of 46 countries having 1000-10000 publications over 5 years, of which 8,6% in medicine. In this article the use of statistics and appropriate software by the authors of original articles in such journals as recommended by the Kazakh National Centre for Scientific & Technical Expertise (NCSTE) and included in the Database еlibrary.kz was evaluated. Research was conducted according to Research Report, due to which a research design and statistical analysis methods were estimated. In the rating of the research design, the authors of articles mostly used as follows: description of a series of cases–63,2%, description of the individual cases -27,1%, and description of specific cases–9,1%. A scope of selection in Section “Research Methods” was only calculated in 21,8% of cases, and in 63,9% of cases there was no description how the selection was carried out. Methods of analytical statistics were used in the 46,0% of cases. And there were references to the program package in use only in 17,5% of works. Thus shown that non-compliance with international standards in the preparation of scientific papers, primarily statistical requirements directly affect the quality and ratings of domestic articles.
- MeSH
- periodika jako téma * MeSH
- publikační zkreslení MeSH
- publikování MeSH
- statistika jako téma * metody normy MeSH
- výzkumný projekt * MeSH
- Geografické názvy
- Kazachstán MeSH
Communication of research findings is the utmost responsibility of all scientists. Publication bias occurs if scientific studies with negative or null results fail to get published. This can happen due to bias in submitting, reviewing, accepting, publishing or aggregating scientific literature that fails to show positive results on a particular topic. Publication bias can make scientific literature unrepresentative of the actual research studies. This can give the reader a false impression about the beneficial effects of a particular treatment or intervention and can influence clinical decision making. Publication bias is more common than it is actually considered to be, but there are ways to detect and prevent it. This paper comments on the occurrence, types and consequences of publication bias and the strategies employed to detect and control it.
- MeSH
- antipsychotika MeSH
- hodnocení léčiv MeSH
- konflikt zájmů MeSH
- publikační zkreslení MeSH
- Publikační typ
- klinické zkoušky kontrolované MeSH
- MeSH
- hormonální substituční terapie trendy MeSH
- koronární nemoc prevence a kontrola MeSH
- lidé MeSH
- menopauza účinky léků MeSH
- postmenopauza MeSH
- postmenopauzální osteoporóza účinky léků MeSH
- publikační zkreslení MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- klinické zkoušky kontrolované MeSH
