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In order to facilitate systematic reviews and meta-analyses by medical researchers， this paper provides a tutorial-style review of the relevant concepts， necessary steps， and some key considerations in conducting systematic reviews and meta-analyses. Specifically， it offers detailed explanations on literature search， evaluation of study bias， effect size selection， outcomes pooling， and testing and correction of publication bias. Additionally， the paper provides references to softwares and literature for implementing the methods， and concludes with a brief overview of the requirements for writing research papers.
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Abstract Neuroendocrine tumors (NETs) are relative rare, affecting neuroendocrine cells throughout the body. Most tumors are diagnosed at advanced stages. NETs prevalence has increased in the last years but there is little data available in developing countries. The aim of this study was to describe symptoms associated with NETs in patients of the Society for the Fight Against Cancer (SOLCA) in Ecuador from 2005 to 2020; using logistic biplots, in a hospital database, generating binary responses (presence/absence) relevant to this study. The results showed that the mean age was 59 and the study showed no difference in prevalence between genders. NETs were mainly found in lungs (19%), followed by stomach (18%) and skin (9%). Most patients had pathological diagnosis G2 and G3 (30% and 70%, respectively). Symptoms as cough, dyspnea, weight loss, diarrhea, constipation, abdominal pain, dyspepsia, hypertensive crisis, distended abdomen and intestinal obstruction had p values <0.05. Additionally, the statistical analysis showed that cough and intestinal obstruction were also common, bearing in mind that patients had most frequent NETs in the lungs and skin. In summary, our results indicate that symptoms of NETs patients were positively associated with lung and skin. Further investigation is needed focusing on the type of NETs and their symptoms in order to establish an early marker for diagnosis.
Resumen Los tumores neuroendocrinos (TNE) son relativamente raros y afectan a las células neuroendocrinas de todo el cuerpo. La mayoría de los tumores se diagnostican en etapas avanzadas. La prevalencia de los TNE ha aumentado en los últimos años, pero hay pocos datos en los países en desarrollo. El objetivo de este estudio fue determinar los síntomas asociados a los TNE en pacientes de la Sociedad de Lucha contra el Cáncer (SOLCA) en Ecuador entre 2005 y 2020, utilizando biplots logísticos en una base de datos hospitalaria, generando respuestas binarias (presencia / ausencia) relevantes para este estudio. Los resultados mostraron que la edad promedio era de 59 años y el estudio no encontró diferencias en la prevalencia entre géneros. Los TNE se encontraron con mayor frecuencia en los pulmones (19%), seguidos del estómago (18%) y piel (9%). La mayoría de los pacientes tenían diagnóstico patológico G2 y G3 (30% y 70% respectivamente). Los síntomas como tos, disnea, pérdida de peso, diarrea, estreñimiento, dolor abdominal, dispepsia, crisis hipertensiva, abdomen distendido y obstrucción intestinal tuvieron valores de p <0,05. Además, el análisis estadístico mostró que la tos y la obstrucción intestinal también eran comunes, teniendo en cuenta que los pacientes tenían TNE más frecuentes en los pulmones y la piel. En resumen, nuestros resultados indican que los síntomas de los pacientes con TNE se asociaron positivamente con los pulmones y la piel. Se necesitan más investigaciones que se centren en el tipo de TNE y sus síntomas a fin de establecer un marcador más temprano para el diagnóstico.
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In biostatistics, for each of the specific situation, statistical methods are available for analysis and interpretation of the data. To select the appropriate statistical method, one need to know the assumption and conditions of the statistical methods, so that proper statistical method can be selected for data analysis. Two main statistical methods are used in data analysis: descriptive statistics, which summarizes data using indexes such as mean and median and another is inferential statistics, which draw conclusions from data using statistical tests such as student's t-test. Selection of appropriate statistical method depends on the following three things: Aim and objective of the study, Type and distribution of the data used, and Nature of the observations (paired/unpaired). All type of statistical methods that are used to compare the means are called parametric while statistical methods used to compare other than means (ex-median/mean ranks/proportions) are called nonparametric methods. In the present article, we have discussed the parametric and non-parametric methods, their assumptions, and how to select appropriate statistical methods for analysis and interpretation of the biomedical data.
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Observational study of therapy efficacy comparison has been widely conducted to provide the additional efficacy evidence to support randomized control study. Statistical adjustment for unmeasured confounders is a major challenge in observational study of therapy efficacy comparison. This paper summarizes and evaluates the relative statistical methods. Currently, the most commonly used methods include instrumental variable, difference-in-differences (DiD) model and prior event rate ratio (PERR) adjustment. The instrumental variable method skill fully escapes unmeasured confounders through model structure, but it is not easy to obtain satisfied instrumental variables. Both PERR and DiD require the data prior to exposure which are not always collected in observational studies. Unmeasured confounders could result in new requirements and pose new challenges for statistical methods, which needs further study and improvement.
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Observational comparative effectiveness studies have been widely conducted to provide evidence on additional effectiveness and to support randomized controlled findings in research. Although this type of study becomes more important over time, challenges related to the common biases which stemmed from confounders, are difficult to control. This manuscript summarizes some statistical methods used on adjusting measured confounders that often noticed in research, regarding the observational comparative effectiveness. Useful traditional methods would include stratified analysis, paired analysis, covariate model and multivariable model, etc.. Unconventional adjustment approaches such as propensity score and disease risk score methods may also be used in studies, for matching, stratification and adjustment. A good study design should be able to control confounders. The limitations of all the post hoc statistical adjustment methods should also be fully understood before being appropriately applied in practical events.
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This study aims to explore the evaluation model for the proficiency testing of heavy metal and harmful element residues in pharmaceuticals,and to provide reference for the proficiency testing program and proficiency testing result in the field of residue analysis. The proficiency test result of cadmium determination in honeysuckle as an example. The algorithm A,NIQR,and Horwitz function are used to calculate the assigned value and the standard deviation. Z was obtained at the same time. If | Z | ≤2,the result is satisfactory. If 2< | Z | <3,the result is questionable. If | Z | ≥3,the result is unsatisfactory. In addition,the median value is the assigned value,and deviation(D%) is used. If D% is not more than 16%,the result is satisfactory; if D% is more than 16%,the result is unsatisfactory. After analysis,in the results of questionable or dissatisfied laboratories calculated by algorithm A and NIQR,the deviation error of some data is within the scope of the standard. In the results of the satisfactory laboratory evaluated by the Horwitz function,some data deviation errors far exceed the standard range. The evaluation result of the D% meets the requirements. According to heavy metal and harmful element trace analysis methods,this study is the first to apply D% to the evaluation of the detection ability of heavy metals and harmful elements in pharmaceuticals. This method makes the evaluation result more reasonable,and has important reference significance for the evaluation of other proficiency test results.
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Cadmium , Laboratories , Laboratory Proficiency Testing , Lonicera , Chemistry , Pharmaceutical Preparations , Reference Standards , Plant Preparations , Reference Standards , Trace ElementsABSTRACT
Objective To investigate the statistical methods used in nursing papers for bachelor's degree. Method We collected 160 nursing theses for bachelor's degree in 2016 in our college and analyze the statistical methods. Results A total of 80 papers used statistical methods consisting of statistical table, statistical inference, single factor analysis, variance analysis and statistical description. Among them, the statistical methods in 66 papers (82.5%) were misused. About 139 misuses of statistical tables was found in papers, and about 23 misuses of statistical inference in papers, taking up 45.4%. Conclusions The nursing undergraduates are familiar with the application of statistical methods, but the methods tend to be simple and unitary. Therefore, it is a need to enhance their practice in using statistical methods.
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OBJECTIVE: To explore the statistical methods for proficiency testing in the drug control field. METHODS: The statistical methods were sorted out with data processing used in inter-laboratory and proficiency testing by various industries both at home and abroad. The Grubbs test and Dixon test in classical statistical method were focused on as well as quartile method and iterative method in the robust statistical method, and the characteristics of the different statistic methods was summarized respectively. RESULTS: Every method has its advantages and application conditions. CONCLUSION: It is suggested that proper statistical method be chosen according to the data characteristics of the test results.
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OBJECTIVE: To compare two biological standardization calculation methods for evaluating the anticoagulation activity of different leeches in the same measure. METHODS: Heparin was used as the reference substance. The APTT values of W. pigra, H. nipponica and P. manillensis were used as the anticoagulant activity evaluation potency. The slope ratio model of European Pharmacopoeia 7.0 and the parallel reaction model of Ch.P 2015 were used to calculate the activity and the results were compared. RESULTS: The logarithm dose response curves of three kinds of leeches displayed linear relationship. Both of biological standardization statistical methods could be used for the calculation. The slope ratio model complete randomized design(0, 3, 3) of European Pharmacopoeia 7.0 was suitable to calculate the activity potency of different leeches, but the parallel reaction model of Chinese Pharmacopoeia 2015 was only suitable for P. manillensis. CONCLUSION: Taking the anticoagulation potency of heparin sodium as the reference, the slope ratio model complete randomized design(0, 3, 3) of European Pharmacopoeia 7.0 can be used as a standard method to evaluate the anticoagulation activity of different leeches.
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OBJECTIVE: To evaluate the frequency and adequacy of statistical analyses in a general radiology journal when reporting a reliability analysis for a diagnostic test. MATERIALS AND METHODS: Sixty-three studies of diagnostic test accuracy (DTA) and 36 studies reporting reliability analyses published in the Korean Journal of Radiology between 2012 and 2016 were analyzed. Studies were judged using the methodological guidelines of the Radiological Society of North America-Quantitative Imaging Biomarkers Alliance (RSNA-QIBA), and COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) initiative. DTA studies were evaluated by nine editorial board members of the journal. Reliability studies were evaluated by study reviewers experienced with reliability analysis. RESULTS: Thirty-one (49.2%) of the 63 DTA studies did not include a reliability analysis when deemed necessary. Among the 36 reliability studies, proper statistical methods were used in all (5/5) studies dealing with dichotomous/nominal data, 46.7% (7/15) of studies dealing with ordinal data, and 95.2% (20/21) of studies dealing with continuous data. Statistical methods were described in sufficient detail regarding weighted kappa in 28.6% (2/7) of studies and regarding the model and assumptions of intraclass correlation coefficient in 35.3% (6/17) and 29.4% (5/17) of studies, respectively. Reliability parameters were used as if they were agreement parameters in 23.1% (3/13) of studies. Reproducibility and repeatability were used incorrectly in 20% (3/15) of studies. CONCLUSION: Greater attention to the importance of reporting reliability, thorough description of the related statistical methods, efforts not to neglect agreement parameters, and better use of relevant terminology is necessary.
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Biomarkers , Diagnostic Tests, Routine , MethodsABSTRACT
OBJECTIVE: To explore rational statistical methods for analysis of the results of inter-laboratory comparisons, which will be helpful to improve the statistical analysis ability of organizers of proficiency testing project against pharmaceutical laboratories. METHODS: Robust statistical Z-score method and iterative computation method were used to analyze the assay result of cefminox sodium powder for injection respectively, and the critical statistical parameters of the two methods were compared. RESULTS: The critical statistical parameters of robust statistical Z-score method anf iterative computation method were as follows: the robust average were 77.71% and 77.63%, the robust standard deviation were 0.66 and 0.67, and the coefficients of variation were 0.85% and 0.86%, respectively. CONCLUSION: It is very important to select the correct statistical approach to evaluate the proficiency of pharmaceutical testing laboratories. By comparing the steady average and the median value of Z-score, the range of best estimates for the true value can be found, and the judgment for the outliers can be more accurate.
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External quality assessment (EQA)as an effective tool for quality control can help clinical laboratories to discover quality problems during testing process and prompt clinical laboratories to improve their testing quality.Samples used for traditional EQA frequently have matrix effects which assign the target value by grouping.Ideal samples for EQA are com-mutable which have the same numeric relationship between different measurement procedures as that expected for patients’ samples.And they can assess accuracy against a reference measurement procedure or a designated comparison method.When analyzing,robust statistical method can be used to reflect the variability of testing results between laboratories more truly. And the evaluation standards should be desirable.If unsatisfactory results appear,we should investigate every aspect of tes-ting process,find the root cause,and take corrective action.On condition that no official EQA scheme is launched for some analytes,it is necessary for us to evaluate the performance of analytes by alternative evaluation procedures.
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PURPOSE: Use of inappropriate statistical methods may lead to incorrect conclusions and a waste of valuable resources. The goal of this study was to assess the frequency and the types of several common statistical errors in the published articles of the Journal of the Korean Academy of Prosthodontics (JKAP) for a 5-year period. MATERIALS AND METHODS: Of 336 articles in the JKAP published from 2006 to 2010, 255 articles using statistics were reviewed and classified by statistical method and year. The frequency and types of the statistical methods were examined, and the statistical errors were evaluated by the appropriateness of the experimental design, assumption check, independent outcomes, proper sample size and suitable use of statistical method. Statistical guidelines were completed based on the appropriateness. RESULTS: Of the 255 articles using statistics, 193 articles (75.9%) used inferential statistics and 153 articles used SPSS statistical software (60.0%). Of the articles using inferential statistics, the three most frequently used statistical methods were ANOVA (41.5%), t-test (20.0%), and the nonparametric method (16.9%). The average rate of statistical errors was 61.2 percent, similar to the rate reported by several studies completed for the medical journal. CONCLUSION: After the whole analysis of the difference among the groups, post-hoc tests for the pairwise comparisons are required. The optimal sample size calculation is an essential part of this study protocol. To minimize the occurrence of statistical errors, statistical guidelines were developed according to each statistical test procedure and will contribute to the academic improvement in the JKAP.
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Prosthodontics , Research Design , Sample SizeABSTRACT
BACKGROUND: This study proposed a desirable direction for the future development of the Korean Journal of Family Medicine (KJFM) by comparing with the overseas SCI journals, Family Medicine (FM) and The Journal of Family Practice (JFP) based on the statistical viewpoints. METHODS: All of the original articles published in KJFM from January 1981 to June 2011, FM from January 1998 to June 2011, and JFP from January 1978 to June 2011, were reviewed and compared in terms of content, data size, research design, and statistical method. RESULTS: Of 3,226 total original articles, KJFM published 1,549, FM 322, and JFP 1,355, respectively. Both JFP and KJFM mainly focused on biomedical topics (67.2% and 61.7%), while FM focused on education (55.9%). Most of the studies in three journals used the data size of between 100 to 300 cases. The most frequently used research design was cross-sectional, FM 66.8%, JFP 58.4%, and KJFM 72.4%, respectively. The statistical methods in KJFM were gradually diversified. CONCLUSION: The quality of the original articles in KJFM has been improved over the years, but still has conducted based on the relatively weak research designs. Under the circumstances that the higher ranked SCI journals demand the prospective design and large size of data, and most researchers in Korea could not use the large scaled prospective data, we need to collaborate to accumulate the small sized data sets and try to make a registry. More refined statistical method such as a propensity score matching analysis for retrospective data could be an alternative.
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Humans , Family Practice , Korea , Propensity Score , Research DesignABSTRACT
Rules, formulas and statistical tests have been widely used in studies that use continuous variables in the normal or Gaussian distribution or other tests whose data fit this type of distribution (t and z distributions) and whose parameters can be defined. However, there are cases in which the model and goal of the scientific work allow only the use of discrete or nominal variables. The absence or presence of a structure or organ (muscles, nerves, blood vessels, bones, and ligaments), characteristics associated with these organs, such as the source of nerves, vessels and muscles and the distribution of nerves and vessels are discrete and / or nominal variables that do not fit the Gaussian distribution, nor of z or t, unless the measures of these structures are taken. A simple comparative method within the non-parametric distribution has been proposed, (1) between two different samples from the same species and (2) for two different species, based on the concepts of normal and variation in anatomy and on modal class in statistics here called Comparative Anatomy Index (IAC). The main findings on the use of this method are: (1) to allow the relationship between data from discrete or nominal variables in comparative anatomy or in other areas of morphology, (2) to generate an objective method (numerical) of comparison between samples of structures from the same species and between different species and (3) to fill the lack of a specific method for the statistical work in comparative anatomy or in morphology, in general.
Normas, fórmulas y pruebas estadísticas han sido ampliamente utilizadas en estudios que utilizan las variables continuas en el desarrollo de la distribución normal o de Gauss, u otras pruebas, cuyos datos se ajustan a esta tipo de distribución (t y z distribuciones), y cuyos parámetros pueden ser definidos. Sin embargo, hay casos en que el modelo y el objetivo de los trabajos científicos sólo permiten la uso de variables nominales o discretas. La ausencia o presencia de un estructura u órgano (músculos, nervios, vasos sanguíneos, huesos y ligamentos), las características asociadas a estos órganos, como la fuente de los nervios, los músculos y los buques y la distribución de los nervios y los buques son discretos y / o variables nominales que no encajan en el curva de Gauss, ni de z o t, a menos que las medidas de estos estructuras se toman. Un simple método comparativo dentro de la no-paramétrico de la distribución se ha propuesto, (1) entre dos muestras de la misma especie y (2) de dos especies diferentes, con base en los conceptos de normal y la variación en la anatomía y de la clase modal en estadísticas aquí llamado Índice Anatomíca Comparada (IAC). Los principales conclusiones sobre el uso de este método son: (1) para permitir que la relación entre los datos de las variables nominales o discretos en la anatomía comparada o en otras áreas de la morfología, (2) para generar un método objetivo (numérico), de la comparación entre muestras de las estructuras de la misma especies y entre diferentes especies, (3) para cubrir la falta de un método específico para la labor estadística en la anatomía comparada o en morfología, en general.
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Anatomy, Comparative , Statistics as Topic/methodsABSTRACT
Tumor genesis and development often result from deregulation of important biological pathways at the gene expression level. Although there has been much work focused on searching gene sets using gene expression data or other prior information, proper statistical testing of the gene sets is still an open question. Most studies have expanded the testing method of a single gene into the gene sets. Parametric statistical analysis of gene sets ( p-SAGE ) was presented for determining the significant gene sets or pathways associated with a phenotype of interest. The method was applied to brain tumor experiments to identify many gene sets. Some of the newly discovered gene sets were related to signal transduction and immunity. This simple and effective method gives useful biologically meaningful results.
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STATEMENT OF PROBLEM: The aim of dental research is to advance scientific knowledge and leads to improvement in the treatment and prevention of dental disease. Utilizing an effective research design and adequate statistical methods are essential procedures ensuring that the results of researches are based on evidences. A research should utilize proper statistical methods without statistical errors; Otherwise, it could adversely affect clinical practice and future research. PURPOSE: This study was made to investigate the statistical methods used in the Journal of Korean Academy of Prosthodontics (JKAP) and then to assess them for the statistical errors. MATERIAL AND METHODS: Among the total of 399 articles in the JKAP published from 2000 to 2006, 292 articles using statistics were reviewed. The validity of the statistical methods used in them were assessed using a checklist based on the guideline for statistical reporting in the uniform requirements for manuscripts submitted to biomedical journals by International Committee of Medical Journal Editors. The checklist consisted of three categories of statistical errors: 1) Unspecified computer statistical packages, 2) Inadequate description of statistical methods, 3) Misuse of statistical terms. Then, the results were compared between the Korean version and the English version in the JKAP. RESULTS: Among the 212 articles using statistics in the Korean version, 115 articles (54%) and among the 80 articles using statistics in the English version, 47 articles (59%) were shown to have unspecified computer statistical packages without statistically significant difference (P = .66). Likewise, 101 articles (48%) in the Korean version and 25 articles (31%) in the English version were shown to have the inadequate description of statistical methods without statistically significant difference (P = .09). However, 114 articles (54%) in the Korean version and 19 articles (24%) in the English version were shown to have the misuse of statistical terms with statistically significant difference (P = .01). CONCLUSION: Some of the articles in the JKAP had inadequate statistical validity, given the statistical errors identified in this assessment. Hence, dental researchers should be more careful when it comes to describing and applying statistical methods.
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Checklist , Dental Research , Prosthodontics , Research Design , Stomatognathic DiseasesABSTRACT
With the expanding scale of animal cell culture and increasing demand of biopharmaceutical,the development of serum-free medium based on cell lines and products has become a major task in the field of cell engineer.The statistical methods and tools are popular in the processes of design medium and can be used to evaluate the multiple factors and their interaction scientifically and effectively.The novel microarray and proteomic analysis can improve the performance of identifying the role of medium.The aim is to provide some idea for serum-free medium study through systematically summarizing the newly and commonly used serum-free medium study and design approaches and their characteristics.
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Various statistical techniques are used increasingly by researchers in the fields of physical fitness and sports medicine. Nowadays, most researchers have a tendency to rely on statistical packages and distant memories of poorly understood lectures on statistics. Researchers need not know how to calculate the statistics from the data but are required to select the most appropriate technique from the statistical packages and interpret the statistical results accurately. Therefore, this lecture focused on proper usage of statistical techniques and appropriate interpretation of statistical results for the researchers of physical fitness and sports medicine.
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The statistical analysis is an essential procedure ensuring that the results of researches are based on evidences rather than opinion. The purpose of this study is to evaluate the statistical methods and errors in JKPRS and to propose improvement plan.We reviewed 326 articles published in JKPRS between 1996 and 1999. We evaluated the validity of used statistical methodology with our own checklist based on "Guideline for statistical reporting in articles for medical journals" by "International committee of medical journal editors". Among 326 articles, case(series) report and original articles were 167(51.2%) and 156(47.9%) respectively. In 159(48.8%) papers statistical method was not used. In 94 (28.8%) papers, only descriptive methods were used, while in 73 papers(22.4%) descriptive and inferential methods were used. The papers published in 1999 used more statistical methods than in 1996. Among the papers which used descriptive method, 90 papers(53.0%) showed appropriate central tendency and dispersion. But, in papers which used inferential method, 24 papers(33.0%) applied appropriate methods and only 4 papers(5.5%) were satisfactory in utilization of statistical methodology. It is suggested that more consultation of investigators with bio-statisticians, a basic training on statistical methods in resident programs, and more extensive statistical refereeing are needed.