Japanese journal of biometrics最新文献_第9页

Statistical Approaches to Multiplicity Issues in Clinical Trials 临床试验中多重性问题的统计方法

Japanese journal of biometrics Pub Date : 2008-07-01 DOI: 10.5691/JJB.29.S15

T. Morikawa

引用次数: 1

Effective Size of Age-Structured Populations with Cyclic Change in Size 规模周期性变化的年龄结构种群的有效规模

Japanese journal of biometrics Pub Date : 2008-06-01 DOI: 10.5691/JJB.29.45

T. Nomura

引用次数: 1

A Modification of the 50 %-Conditional Power Approach for Increasing the Sample Size Based on an Interim Estimate of Treatment Difference 基于处理差异中期估计的增加样本量的50%条件功率法的修正

Japanese journal of biometrics Pub Date : 2008-06-01 DOI: 10.5691/JJB.29.19

K. Uemura, Y. Matsuyama, Y. Ohashi

{"title":"A Modification of the 50 %-Conditional Power Approach for Increasing the Sample Size Based on an Interim Estimate of Treatment Difference","authors":"K. Uemura, Y. Matsuyama, Y. Ohashi","doi":"10.5691/JJB.29.19","DOIUrl":"https://doi.org/10.5691/JJB.29.19","url":null,"abstract":"Recently, flexible approaches with updating of sample size during the course of clinical trials have been proposed; the weighted Z-statistic approach and the 50 %-conditional power approach. In this paper, we propose a modification of the 50 %-conditional power approach, which increases the sample size only when the conditional power based on the unblinded interim results is greater than 50 %. Our method can control the type I error rate due to the restriction on the minimum required sample size ratio under the decision of increasing sample size. Simulation studies showed that the proposed method increased power about 10 % compared with the fixed sample size design and attained higher power than the original 50 %-conditional power approach. Compared with the weighted Z-statistic approach, the proposed method had several promising operating characteristics; a substantial gain in conditional power given the decision of sample size adjustment, a low probability of reaching the maximum sample size, a substantial decrease in the conditional type II error rate given the maximum sample size, and a conservative property of not increasing sample size erroneously under no treatment effect.","PeriodicalId":365545,"journal":{"name":"Japanese journal of biometrics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127508368","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}

引用次数: 2

Mixture Models for Mixed Poisson Processes with Baseline Counts in Randomized Controlled Trials 随机对照试验中具有基线计数的混合泊松过程混合模型

Japanese journal of biometrics Pub Date : 2008-06-01 DOI: 10.5691/JJB.29.1

H. Uehara, T. Tango

引用次数: 0

Fixation Probability of a Neutral Gene in an Age-Structured Population with Cyclic Change in Size 中性基因在大小周期性变化的年龄结构群体中的固定概率

Japanese journal of biometrics Pub Date : 2008-06-01 DOI: 10.5691/JJB.29.35

T. Nomura

引用次数: 1

Survival Analysis for Gastric Cancer Using the Japanese Foundation Database Based on a Generalized Hazards Model Incorporating B-spline Functions 基于b样条函数的广义风险模型的胃癌生存分析

Japanese journal of biometrics Pub Date : 2007-12-01 DOI: 10.5691/JJB.28.59

Hisao Takeuchi, I. Yoshimura, C. Hamada

{"title":"Survival Analysis for Gastric Cancer Using the Japanese Foundation Database Based on a Generalized Hazards Model Incorporating B-spline Functions","authors":"Hisao Takeuchi, I. Yoshimura, C. Hamada","doi":"10.5691/JJB.28.59","DOIUrl":"https://doi.org/10.5691/JJB.28.59","url":null,"abstract":"The Japanese Foundation for Cancer Research (JFCR) has provided a large database on gastric cancer for open use comprised of data on survival times after surgery and related covariates including prognostic factors. Data analysis based on the generalized hazards model incorporating the B-spline function (GHMBS) was performed using a dataset (JFCR dataset) composed of 9,631 cases within this database. A model selection method was adopted for clarifying the meaning of estimated parameters, because the GHMBS was comprised of the proportional hazards model (PHM) and accelerated failure time model (AFTM) as submodels. A preliminary simulation experiment to examine the performance of the model selection method based on the GHMBS was conducted under the condition that multiple covariates were considered, where one was the target covariate and the other was covariate for adjustment. After validation of the method by this simulation experiment, the method was applied to the JFCR dataset to estimate the period effect for prolonging survival time with an adjustment for the stage effect. The analysis revealed that the PHM was suitable for the period effect, while a mixture of the PHM and AFTM was for the stage effect and treatment for gastric cancer made steady progress from the 1950s through the 1990s.","PeriodicalId":365545,"journal":{"name":"Japanese journal of biometrics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125480955","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}

引用次数: 0

Finite Mixture Models in Assessing Anti-thyroglobulin Antibody Positivity as a Marker of Chronic Thyroiditis 有限混合模型评估抗甲状腺球蛋白抗体阳性作为慢性甲状腺炎的标志物

Japanese journal of biometrics Pub Date : 2007-12-01 DOI: 10.5691/JJB.28.79

E. Nakashima, Y. Fujii, M. Imaizumi, K. Ashizawa

{"title":"Finite Mixture Models in Assessing Anti-thyroglobulin Antibody Positivity as a Marker of Chronic Thyroiditis","authors":"E. Nakashima, Y. Fujii, M. Imaizumi, K. Ashizawa","doi":"10.5691/JJB.28.79","DOIUrl":"https://doi.org/10.5691/JJB.28.79","url":null,"abstract":"Positivity of anti-thyroglobulin antibody (TgAb) is one of the markers of chronic thyroiditis (Hashimoto disease). From 2000 to 2003, a thyroid disease prevalence study was conducted at the Radiation Effects Research Foundation, in Hiroshima and Nagasaki. Utilizing the study's results, we show that via EM algorithm log-transformed TgAb level is compatible with a two-component mixture normal distribution, with the smaller normal distribution corresponding to the TgAb negative group but the larger distribution not necessarily corresponding to the TgAb positive group. A subject is determined to be TgAb positive if TgAb level is greater than a given cutoff. We compared the cutoff values from population-based methods and the laboratory method. The population-based methods consist of a simple method, a receiver operating characteristic (ROC) curve method, and a minimum misclassification rate (MMR) method. The simple method is used to determine positivity from only TgAb negative populations. Since the ROC curve and MMR methods are valid only when TgAb positivity and negativity are known but the simple method is valid only when TgAb negativity is known, the simple method was deemed useful for determining the cutoff in our data. In comparison with the simple, population-based method, we show that the cutoff from the laboratory method is appropriate and that the TgAb positive rates from various methods are approximately equal. With the two-component mixture normal distribution in TgAb level, our simple population-based method for determination of cutoff is another more practical example of handling the clinical measurement than the method given in Thompson et al. (Applied Statistics 1998).","PeriodicalId":365545,"journal":{"name":"Japanese journal of biometrics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125425539","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}

引用次数: 1

A Practical Method Adjusting for Publication Bias in Meta-analysis Based on p-value 基于p值调整meta分析发表偏倚的实用方法

Japanese journal of biometrics Pub Date : 2007-07-01 DOI: 10.5691/JJB.28.19

N. Matsuoka, Chihiro Hasegawa, C. Hamada

引用次数: 2

The Q-Q Plot of p-values for Predicting Outcomes with the Gene Expression Data 用基因表达数据预测预后的p值Q-Q图

Japanese journal of biometrics Pub Date : 2007-07-01 DOI: 10.5691/JJB.28.37

Y. Ito, Y. Fujiwara, Y. Ohashi

{"title":"The Q-Q Plot of p-values for Predicting Outcomes with the Gene Expression Data","authors":"Y. Ito, Y. Fujiwara, Y. Ohashi","doi":"10.5691/JJB.28.37","DOIUrl":"https://doi.org/10.5691/JJB.28.37","url":null,"abstract":"Michiels et al. (2005) showed that a list of genes identified as predictors of prognosis via a non-repeated training — validation approach is unstable and advocate the validation by repeated random sampling. They considered that the genes which were selected as top 50 genes in more than half of their jackknife samples were stable for prediction. However, there is no rationale of the determination of the length of the gene list and the threshold of stability. Since evaluating an accumulation of low p-values in the repeated random sampling is essentially required for a stability assessment, it is better to compare the distribution of p-values of a gene observed with the distribution of p-values under the null hypothesis directly. In this study, the Quantile-Quantile plot (Q-Q plot) of p-values with null reference was proposed for this purpose. We applied the proposed method to a clinical data for primary breast cancer. The Q-Q plot approach can reveal that the genes with a similar p-value in the ordinary analysis have different p-value distributions in the repeated random sampling, and the gene with low p-values accumulated in the repeated random sampling could be evaluated according to the reference lines in the Q-Q plot.","PeriodicalId":365545,"journal":{"name":"Japanese journal of biometrics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130532444","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}

引用次数: 0

Comparison of Methods for Parameter Estimation in a Circular Linear Mixed Effect Model Incorporating the Diurnal Variation for Evaluating the Treatment Effects of Glaucoma Therapy 考虑日变化的圆形线性混合效应模型参数估计方法的比较，以评价青光眼治疗效果

Japanese journal of biometrics Pub Date : 2007-07-01 DOI: 10.5691/JJB.28.1

H. Suganami, K. Kano, Y. Kuwayama, C. Hamada, I. Yoshimura

{"title":"Comparison of Methods for Parameter Estimation in a Circular Linear Mixed Effect Model Incorporating the Diurnal Variation for Evaluating the Treatment Effects of Glaucoma Therapy","authors":"H. Suganami, K. Kano, Y. Kuwayama, C. Hamada, I. Yoshimura","doi":"10.5691/JJB.28.1","DOIUrl":"https://doi.org/10.5691/JJB.28.1","url":null,"abstract":"Glaucoma is the primary cause of vision loss in Japan. The most important glaucoma therapy is to decrease intraocular pressure (IOP) for preventing visual field defects in the pre-stage of vision loss. Considering a systematic diurnal variation of IOP, Kuwayama et al. (2006) proposed to use a circular linear mixed effect (CLME) model for evaluating the efficacy of therapy on IOP decrease for patients with normal tension glaucoma (NTG) and applied it to the data analysis in a clinical trial (Nipradilol trial) with 28 NTG patients. In this application, there occurred an issue that the parameter estimates were different depending on the method of estimation and the best method was not identified. We, therefore, compared six methods for parameter estimation (standard two-stage (STS) method, global two-stage (GTS) method, first order approximation (FOA) method, Laplacian approximation (LAP) method, Monte Carlo integration (MCI) method and Gaussian quadrature (GAUS) method) through a simulation experiment with the bias and square root of mean squared error as the criteria for evaluation. The GAUS method proved to be superior to others in realizing least bias and mean squared error under various simulation conditions, although it was most time consuming.","PeriodicalId":365545,"journal":{"name":"Japanese journal of biometrics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126114161","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}

引用次数: 2