Journal of biometrics & biostatistics最新文献

{"title":"Simple Power and Sample Size Estimation for Non-Randomized Longitudinal Difference in Differences Studies.","authors":"Yirui Hu, D R Hoover","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Intervention effects on continuous longitudinal normal outcomes are often estimated in two-arm pre-post interventional studies with b≥1 pre- and k≥1 post-intervention measures using \"Difference-in-Differences\" (DD) analysis. Although randomization is preferred, non-randomized designs are often necessary due to practical constraints. Power/sample size estimation methods for non-randomized DD designs that incorporate the correlation structure of repeated measures are needed. We derive Generalized Least Squares (GLS) variance estimate of the intervention effect. For the commonly assumed compound symmetry (CS) correlation structure (where the correlation between all repeated measures is a constant<i>ρ</i>) this leads to simple power and sample size estimation formulas that can be implemented using pencil and paper. Given a constrained number of total timepoints (T), having as close to possible equal number of pre-and post-intervention timepoints (b=k) achieves greatest power. When planning a study with 7 or less timepoints, given large <i>ρ</i>(<i>ρ</i>≥0.6) in multiple baseline measures (b≥2) or <i>ρ</i>≥0.8 in a single baseline setting, the improvement in power from a randomized versus non-randomized DD design may be minor. Extensions to cluster study designs and incorporation of time invariant covariates are given. Applications to study planning are illustrated using three real examples with T=4 timepoints and <i>ρ</i> ranging from 0.55 to 0.75.</p>","PeriodicalId":87294,"journal":{"name":"Journal of biometrics & biostatistics","volume":"9 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6663085/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141636087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Review of Cancelable Biometric Authentication Methods","authors":"R. Mamatha","doi":"10.4172/2155-6180.1000398","DOIUrl":"https://doi.org/10.4172/2155-6180.1000398","url":null,"abstract":"Biometric analysis for identity verification is becoming a widespread reality. Such implementations necessitate large scale capture and storage of biometric data, which raises serious issues in terms of data privacy and identity theft. Unlike credit cards and passwords, which can be revoked and reissued when compromised, biometrics are permanently associated with a user and cannot be replaced. In order to prevent the theft of biometric patterns, it is desired to modify them through revocable and non-invertible transformations to produce Cancelable biometric templates. This paper provides a review of the state of the art of different methods of biometric based authentication schemes and cancelable biometric systems. Ring finger crease Middle finger crease","PeriodicalId":87294,"journal":{"name":"Journal of biometrics & biostatistics","volume":"09 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4172/2155-6180.1000398","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70292518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The First Statistical Analysis of BUZIM Cancer Types","authors":"Sabahudin Ćordić, Senol Dogan, Lemana Spahić, A. Kozaric","doi":"10.4172/2155-6180.1000400","DOIUrl":"https://doi.org/10.4172/2155-6180.1000400","url":null,"abstract":"Cancer is referred to as malignancy and presented uncontrolled proliferation of cell. Although some of the types are mostly observed, some of them could be in rare amount. Cancer can be affected by many factors including smoking, drinking, obesity, hormones, and environment. Biostatistics is a powerful tool for describing and summarizing different data. This work has been firstly done to analyse the cancer type and rate in Buzim, a city in Bosnia and Herzegovina. According to Buzim main hospital registered data analysis, cancer profiles of the city showed variety of cancer types. Descriptive statistics was used to describe the population and given insight into cancer increasing rate in municipality of the city. By the basic statistical analysis, we understood that digestive and respiratory organs cancer rate more than other and rapidly increased last decade.","PeriodicalId":87294,"journal":{"name":"Journal of biometrics & biostatistics","volume":"09 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4172/2155-6180.1000400","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70292355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Trends of Tuberculosis in Somaliland’s Young Children after the Conflict and the Role Khat Marfishes Play Its Transmission","authors":"Mohamed Hassan","doi":"10.4172/2155-6180.1000397","DOIUrl":"https://doi.org/10.4172/2155-6180.1000397","url":null,"abstract":"After the fall of the central government and the emergence of the recurrent civil conflict in Somalia, many new sociocultural phenomenons that have appeared across the country contributed to the spread of many infectious diseases including TB. One of these social phenomena is a wide spread use of the illicit drug Khat which is predominately used by the Somali males. Mostly khat is chewed in small overcrowded, unhygienic and unventilated makeshift huts known as Marfishes. These Marfishes became the launch pad and the breeding grounds of many infectious diseases that have affected the lives of many Somalis including children. Under-five mortality in somalia is estimated at 200 deaths per 1000 births, which is one of the highest in the world. Approximately one third of these are neonatal deaths, occurring during the first month of life, pneumonia and diarrhea are the main killers each contributing 20-25 percent of all under-five mortality. While these diseases still remained the top major killers, communicable diseases including TB are also a leading cause of death. This paper investigates the incidence and the trends of tuberculosis among the Somali children by using time series statistical models.","PeriodicalId":87294,"journal":{"name":"Journal of biometrics & biostatistics","volume":"12 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4172/2155-6180.1000397","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70292452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prevalence and Risk Factors of Infertility in a Sample of Iranian Couples","authors":"S. Afroughi, M. Pouzesh","doi":"10.4172/2155-6180.1000407","DOIUrl":"https://doi.org/10.4172/2155-6180.1000407","url":null,"abstract":"","PeriodicalId":87294,"journal":{"name":"Journal of biometrics & biostatistics","volume":"09 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4172/2155-6180.1000407","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70292658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Power Estimation in Planning Randomized Two-Arm Pre-Post Intervention Trials with Repeated Longitudinal Outcomes.","authors":"Yirui Hu,&nbsp;Donald R Hoover","doi":"10.4172/2155-6180.1000403","DOIUrl":"https://doi.org/10.4172/2155-6180.1000403","url":null,"abstract":"<p><strong>Background: </strong>Intervention effect on ongoing medical processes is estimated from clinical trials on units (i.e. persons or facilities) with fixed timing of repeated longitudinal measurements. All units start out untreated. A randomly chosen subset is switched to the intervention at the same time point. The pre-post switch change in the outcome between these units and unswitched controls is compared using Generalized Least Squares models. Power estimation for such studies is hindered by lack of available GLS based approaches and normative data.</p><p><strong>Methods: </strong>We derive Generalized Least Squares variance of the intervention effect. For the commonly assumed compound symmetry correlation structure, this leads to simple power formulas with important optimality properties. To maximize power given a constrained number of total time points, we investigate on the optimal pre-post allocation with the local minimization of variance.</p><p><strong>Results: </strong>In four examples from nursing home and HIV patients, the Toepltiz within-unit correlation of repeated measures differed from compound symmetry. We applied empirical Toeplitz based calculations for variance of the estimated intervention effect to these examples (each with up to seven longitudinal measures). Unlike what happened under compound symmetry, where power was often maximized with multiple observations being pre-intervention, for these examples, having one pre-intervention measure tended to maximize power. Attempts to approximate the Toeplitz variance structures with compound symmetry (to take advantage of the simpler formulas) resulted in overestimation of power for these examples.</p><p><strong>Conclusions: </strong>While compound symmetry correlation among repeated within-unit measures leads to simple power estimation formulas, this structure often did not hold. There may be strong underestimation of variance of the intervention effect estimate from incorporating short-term within-unit correlation estimates as a common compound symmetry correlation to approximate an unknown Toeplitz correlation without adequately accounting for the correlation between repeated measures declining with time.</p>","PeriodicalId":87294,"journal":{"name":"Journal of biometrics & biostatistics","volume":"9 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4172/2155-6180.1000403","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"36639590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unrestricted Normal Distribution Type Symmetry Model for Square Contingency Tables with Ordered Categories","authors":"Yusuke Saigusa, Shimpei Goda, K. Yamamoto, S. Tomizawa","doi":"10.4172/2155-6180.1000395","DOIUrl":"https://doi.org/10.4172/2155-6180.1000395","url":null,"abstract":"","PeriodicalId":87294,"journal":{"name":"Journal of biometrics & biostatistics","volume":"09 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4172/2155-6180.1000395","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70292111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on Outlier Detection Method in Survival Analysis: Weibull Regression Outlier Model","authors":"Chang Shu, T. Qin, Xiao-ping Chen, P. Yin","doi":"10.4172/2155-6180.1000410","DOIUrl":"https://doi.org/10.4172/2155-6180.1000410","url":null,"abstract":"","PeriodicalId":87294,"journal":{"name":"Journal of biometrics & biostatistics","volume":"09 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4172/2155-6180.1000410","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70293276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Statistical Analysis of Factors that Affect the Use of Maternal Health Care Services in Gubure Sub-City: SNNP, Ethiopia","authors":"G. M. Alemayehu","doi":"10.4172/2155-6180.1000399","DOIUrl":"https://doi.org/10.4172/2155-6180.1000399","url":null,"abstract":"Background: Many mothers suffer from complications of pregnancy and delivery problems. Complications of pregnancy and childbirth are a leading cause of maternal morbidities and mortalities in developing countries. The WHO estimates that over 500,000 women and girls die each year from the complications and mortality of mothers lack of antenatal visit care is high in Gubre city. Objective: The aim of this research is to identify the factors that affect the use of maternal health care service. Methodology: The study was conducted by using simple random sampling and samples size was selected by lottery method and the total sample size selected was 145 out of 1624 total population. The research was conducted by using primary data and the collected data were analysed by statistical software SPSS version 23, and binary Logistic regression analysis was used to analyse the data. Results: Based on this analysis marital status, occupation, immunization, background of maternal health services, existence of adequate health services were the major factors on the use of maternal health care services. Conclusion: From the findings we conclude that many of women are not the user of services because of there is no adequate health services as well as there is no essential information in the population. Therefore we would like to inform to the Gubre sub city that have authority to distribute maternal health services as they constructs for this area and to provide enough treatment for mother’s and for all female’s. The researchers recommend that appropriate intervention should be done by the government, and the health concerned body. Citation: Alemayehu GM (2018) Statistical Analysis of Factors that Affect the Use of Maternal Health Care Services in Gubure Sub-City: SNNP, Ethiopia. J Biom Biostat 9: 399. doi: 10.4172/2155-6180.1000399","PeriodicalId":87294,"journal":{"name":"Journal of biometrics & biostatistics","volume":"09 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4172/2155-6180.1000399","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70292142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Classical and Robust Forward Selection: A Simulation Study and Real Data Application","authors":"Moushumi Pervin, M. Rahman","doi":"10.4172/2155-6180.1000404","DOIUrl":"https://doi.org/10.4172/2155-6180.1000404","url":null,"abstract":"In order to use any method as a model selection algorithm, it is needed to check the adequacy and stability of a model selected by the algorithm. Adequacy of a robust model was not checked by giving outliers in various ways. In this paper, several contamination cases have been introduced to check the adequacy of the robust model selected by robust forward selection (RFS). In each of the contamination case, the performance of RFS has been compared to standard forward selection (FS) through a simulation study. The adequacy and stability of the robust model has also been checked through a real data application. Based on simulation study and real data application, RFS has much better performance compared to standard FS.","PeriodicalId":87294,"journal":{"name":"Journal of biometrics & biostatistics","volume":"9 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4172/2155-6180.1000404","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70292831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}