Differences in surrogate threshold effect estimates between original and simplified correlation-based validation approaches.

abstract：:Timeliness of a public health surveillance system is one of its most important characteristics. The process of predicting the present situation using available incomplete information from surveillance systems has received the term nowcasting and has high public health interest. Generally in Europe, general practitione...

journal_title：Statistics in medicine

authors： Nunes B,Natário I,Lucília Carvalho M

更新日期：2013-07-10 00:00:00

abstract：:In many chronic diseases, therapy aims to prevent or reduce the frequency of episodes of a disease manifestation, for example cardiac ischaemic episodes or epileptic seizures. Entry criteria for clinical trials typically include a minimum number of episodes within a baseline period, and regression to the mean should b...

journal_title：Statistics in medicine

authors： McMahon RP,Proschan M,Geller NL,Stone PH,Sopko G

更新日期：1994-04-30 00:00:00

abstract：:This paper investigates the Bayesian procedures for comparing proportions. These procedures are especially suitable for accepting (or rejecting) the equivalence of two population proportions. Furthermore the Bayesian predictive probabilities provide a natural and flexible tool in monitoring trials, especially for choo...

journal_title：Statistics in medicine

authors： Lecoutre B,Derzko G,Grouin JM

更新日期：1995-05-15 00:00:00

abstract：:It has been increasingly common to analyze simultaneously repeated measures and time to failure data. In this paper we propose a joint model when the repeated measures are semi-continuous, characterized by the presence of a large portion of zero values, as well as right skewness of non zero (positive) values. Examples...

journal_title：Statistics in medicine

authors： Liu L

更新日期：2009-03-15 00:00:00

abstract：:Log-linear models for capture-recapture type data are widely used for estimating sizes of populations. Log-linear methods model conditional interactions between the sources. Often, however, the marginal associations are more appropriate and easier for the practitioner to conceptualize. Analyses here of previously publ...

journal_title：Statistics in medicine

authors： Regal RR,Hook EB

更新日期：1998-01-15 00:00:00

abstract：:If the sample size for a t-test is calculated on the basis of a prior estimate of the variance then the power of the test at the treatment difference of interest is not robust to misspecification of the variance. We propose a t-test for a two-treatment comparison based on Stein's two-stage test which involves the use ...

journal_title：Statistics in medicine

authors： Denne JS,Jennison C

更新日期：1999-07-15 00:00:00

abstract：:The introduction of potent antiretroviral therapies for treatment of HIV infection typically results in a dramatic reduction in plasma HIV RNA concentration, often to levels undetectable by current measurement practices. However, although a high proportion of patients achieve 'undetectability', many then experience a ...

journal_title：Statistics in medicine

authors： McKinnon EJ,James IR,John M,Mallal SA

更新日期：2003-02-15 00:00:00

abstract：:Many split-mouth trials are characterized by the pairing of site-specific outcome and baseline data within each segment of a subject's mouth. However when the response variable of interest is binary, methods of statistical analysis for this design are not well developed. In this paper we present several analytic appro...

journal_title：Statistics in medicine

authors： Donner A,Zou GY

更新日期：2007-08-15 00:00:00

abstract：:We present a new approach to training back-propagation artificial neural nets (BP-ANN) based on regularization and cross-validation and on initialization by a logistic regression (LR) model. The new approach is expected to produce a BP-ANN predictor at least as good as the LR-based one. We have applied the approach to...

journal_title：Statistics in medicine

authors： Ciampi A,Zhang F

更新日期：2002-05-15 00:00:00

abstract：:Analyses to compare non-randomized groups are more and more common in both post hoc analyses of randomized clinical trials data and in analyses of long-term observational data. In such cases, it is quite likely that there are unknown or uncollected sources of heterogeneity in event rates. Research has shown that an un...

journal_title：Statistics in medicine

authors： Eberly LE

更新日期：2004-07-15 00:00:00

abstract：:Omitted variable bias is discussed in the context of linear models. It is shown that the effect of omitted variables can be controlled in linear models for metric dependent variables by using data from follow-up studies. Two different models for analysing such data are proposed. In the first model the omitted variable...

journal_title：Statistics in medicine

authors： Rehm J,Arminger G,Kohlmeier L

更新日期：1992-06-30 00:00:00

abstract：:Longitudinal studies collect information on a sample of individuals which is followed over time to analyze the effects of individual and time-dependent characteristics on the observed response. These studies often suffer from attrition: individuals drop out of the study before its completion time and thus present inco...

journal_title：Statistics in medicine

authors： Alfò M,Maruotti A

更新日期：2009-08-30 00:00:00

abstract：:Both the variation of positive responses (negative responses) among individuals and the internal correlation among responses for the same individual affect the precision of the estimate of sensitivity (specificity). To estimate the sensitivity (specificity) of a medical diagnostic test, this paper proposes a Bayesian ...

journal_title：Statistics in medicine

authors： Lui KJ

更新日期：1989-10-01 00:00:00

abstract：:In the recent two decades, data mining methods for signal detection have been developed for drug safety surveillance, using large post-market safety data. Several of these methods assume that the number of reports for each drug-adverse event combination is a Poisson random variable with mean proportional to the unknow...

journal_title：Statistics in medicine

authors： Hu N,Huang L,Tiwari RC

更新日期：2015-08-30 00:00:00

abstract：:The incremental life expectancy, defined as the difference in mean survival times between two treatment groups, is a crucial quantity of interest in cost-effectiveness analyses. Usually, this quantity is very difficult to estimate from censored survival data with a limited follow-up period. The paper develops estimati...

journal_title：Statistics in medicine

authors： Titman AC

更新日期：2016-09-10 00:00:00

abstract：:In standard time-to-event or survival analysis, occurrence times of the event of interest are observed exactly or are right-censored, meaning that it is only known that the event occurred after the last observation time. There are numerous methods available for estimating the survival curve and for testing and estimat...

journal_title：Statistics in medicine

authors： Lindsey JC,Ryan LM

更新日期：1998-01-30 00:00:00

abstract：:The relative concentration index (RCI) and the absolute concentration index (ACI) have been widely used for monitoring health disparities with ranked health determinants. The RCI has been extended to allow value judgments about inequality aversion by Pereira in 1998 and by Wagstaff in 2002. Previous studies of the ext...

journal_title：Statistics in medicine

authors： Yu M,Liu B,Li Y,Zou ZJ,Breen N

更新日期：2019-01-15 00:00:00

abstract：:In this commentary, we revisit Sir Austin Bradford Hill's seminal Alfred Watson Memorial Lecture in 1962 through the eyes of two practicing biostatisticians of the current era. We summarize some eternal takeaway messages from Hill's lecture regarding observations and experiments translated through the modern lexicon o...

journal_title：Statistics in medicine

authors： Dempsey W,Mukherjee B

更新日期：2021-01-15 00:00:00

abstract：:Confidence intervals for a standardized effect are derived after stabilizing the variance of the Welch t-statistic. Simulation studies demonstrate the viability of the resulting intervals for a wide range of parameter values and sample sizes as small as five. The methodology is extended to the combination of results f...

journal_title：Statistics in medicine

authors： Kulinskaya E,Staudte RG

更新日期：2007-06-30 00:00:00

abstract：:Although prostate cancer and benign prostatic hyperplasia are major health problems in U.S. men, little is known about the early stages of the natural history of prostate disease. A molecular biomarker called prostate specific antigen (PSA), together with a unique longitudinal bank of frozen serum, now allows a histor...

journal_title：Statistics in medicine

authors： Pearson JD,Morrell CH,Landis PK,Carter HB,Brant LJ

更新日期：1994-03-15 00:00:00

abstract：:Health surveillance involves collecting public health data on chronic and infectious diseases to detect changes in disease incidence rates in order to improve public health. Timely detection of disease clusters is essential in prospective public health surveillance. Most existing health surveillance research is based ...

journal_title：Statistics in medicine

authors： Jiang W,Han SW,Tsui KL,Woodall WH

更新日期：2011-02-28 00:00:00

abstract：:This paper gives a standard error for Cohen's Kappa, conditional on the margins of the observed r x r table. An explicit formula is given for the 2 x 2 table, and a procedure for the more general situation. A parsimonious log-linear model is suggested for the general case and an approximate confidence interval for kap...

journal_title：Statistics in medicine

authors： Garner JB

更新日期：1991-05-01 00:00:00

abstract：:During phase III clinical trials in life-threatening disease settings, it is important to ensure that the Data Monitoring Committee (DMC) has exclusive access to the interim efficacy and safety data generated by the data analysis centre, in order to minimize the risk of widespread prejudgement of unreliable trial resu...

journal_title：Statistics in medicine

authors： Fleming TR,Ellenberg S,DeMets DL

更新日期：2002-10-15 00:00:00

abstract：:The construction, validation and updating of a prognostic model for kidney graft survival is reported using data from the Eurotransplant database. First, a model is constructed for data from transplantations in the period 1984 to 1987. The model is later updated for the 1988 1990 data. The first data set was randomly ...

journal_title：Statistics in medicine

authors： Van Houwelingen HC,Thorogood J

更新日期：1995-09-30 00:00:00

abstract：:In repeated measures settings, modeling the correlation pattern of the data can be immensely important for proper analyses. Accurate inference requires proper choice of the correlation model. Optimal efficiency of the estimation procedure demands a parsimonious parameterization of the correlation structure, with suffi...

journal_title：Statistics in medicine

authors： Simpson SL,Edwards LJ,Muller KE,Sen PK,Styner MA

更新日期：2010-07-30 00:00:00

abstract：:In longitudinal studies, missing observations occur commonly. It has been well known that biased results could be produced if missingness is not properly handled in the analysis. Authors have developed many methods with the focus on either incomplete response or missing covariate observations, but rarely on both. The ...

journal_title：Statistics in medicine

authors： Li H,Yi GY

更新日期：2013-02-28 00:00:00

abstract：:Non-tumor cell-based model systems have recently gained interest in pharmacogenetic research as a hypothesis generating tool. The hypotheses generated from these model systems can be followed up in functional studies, or tested in individuals taking the same investigational agents. The current cellular phenotypes (e.g...

journal_title：Statistics in medicine

authors： Fridley BL,Jenkins G,Schaid DJ,Wang L

更新日期：2009-09-20 00:00:00

abstract：:The proposed guidelines for the assessment of the effect of new pharmaceutical agents on the QT interval (beginning of QRS complex to end of T wave on the electrocardiogram) are based on the maximum of a series over time of simple one-sided 95 per cent upper confidence bounds. This procedure is typically very conserva...

journal_title：Statistics in medicine

authors： Boos DD,Hoffman D,Kringle R,Zhang J

更新日期：2007-09-10 00:00:00

abstract：:Current methods for statistical analysis of twin studies focus on continuous and dichotomous data, while only limited methodology exists for analysing multinomial data. As a consequence, investigators are often tempted to collapse multinomial data into two categories simply to facilitate the analysis. We address this ...

journal_title：Statistics in medicine

authors： Bartfay E,Donner A

更新日期：2001-01-30 00:00:00

abstract：:In biomedical research such as the development of vaccines for infectious diseases or cancer, study outcomes measured by an assay or device are often collected from multiple sources or laboratories. Measurement error that may vary between laboratories needs to be adjusted for when combining samples across data sources...

journal_title：Statistics in medicine

authors： Huang Y,Huang Y,Moodie Z,Li S,Self S

更新日期：2012-12-10 00:00:00