abstract：:Tsiatis, Rosner, and Mehta (1984, Biometrics 40, 797-803) proposed a procedure for constructing confidence intervals following group sequential tests of a normal mean. This method is first extended for group sequential tests for which the sample sizes between interim analyses are not identical or the times are not equ...

journal_title：Biometrics

authors： Kim K,DeMets DL

更新日期：1987-12-01 00:00:00

abstract：:A log-linear model for estimating the size of a closed population is defined for inverse multiple-recapture sampling with dependent samples. Efficient estimators of the log-linear model parameters and the population size are obtained by the method of minimum chi-square. A chi-square test of the general linear hypothes...

journal_title：Biometrics

authors： Bonett DG,Woodward JA,Bentler PM

更新日期：1987-12-01 00:00:00

abstract：:For the case of repeated measures on Y with mean values linear in a concomitant variable Z in [a, b], a straight-line confidence band over [a, b] is given with width linear in Z. Graphical presentation of such line-segment confidence bands can help emphasize that appropriate inferences are limited to the range of the ...

journal_title：Biometrics

authors： Stewart PW

更新日期：1987-09-01 00:00:00

abstract：:A method is presented for choosing an additive constant c when transforming data x to y = log(x + c). The method preserves Type I error probability and power in ANOVA under the assumption that the x + c for some c are log-normally distributed. The method has advantages similar to those of rank transformations--namely,...

journal_title：Biometrics

authors： Berry DA

更新日期：1987-06-01 00:00:00

abstract：:The distance between homologous DNA sequences of two species is proposed to be -1/4 ln[det(P)], where P is the conditional probability matrix specifying the proportions of the various nucleotides in the second sequence, corresponding to each of the four nucleotides in the first sequence. A probability model is describ...

journal_title：Biometrics

authors： Barry D,Hartigan JA

更新日期：1987-06-01 00:00:00

abstract：:In studies of serial cancer markers or disease states and their relation to survival, data on the marker or state are usually obtained at infrequent time points during follow-up. A Markov model is developed to assess the dependence of risk of death on marker level or disease state and inferences within this model are ...

journal_title：Biometrics

authors： Kay R

更新日期：1986-12-01 00:00:00

abstract：:Consider two independent random variables X and Y. The functional R = Pr(X less than Y) [or gamma = Pr(X less than Y) - Pr(Y less than X)] is of practical importance in many situations, including clinical trials, genetics, and reliability. In this paper several approaches to estimation of gamma when X and Y are presen...

journal_title：Biometrics

authors： Simonoff JS,Hochberg Y,Reiser B

更新日期：1986-12-01 00:00:00

abstract：:Ten parameters extracted from six currently used parametrizations of the four-parameter logistic model, and one new proposal, were examined for their statistical behavior in nonlinear least-squares estimation in combination with ELISA and RIA data. Those which are adequately near-linear on the basis of the Lowry-Morto...

journal_title：Biometrics

authors： Ratkowsky DA,Reedy TJ

更新日期：1986-09-01 00:00:00

abstract：:New drugs that will be investigated in the future are expected to deal with chronic diseases, where the number of patients available for controlled clinical trials will be small and where the long-term sequelae that it is hoped will be ameliorated take a long time to occur. Thus, it would be useful to construct powerf...

journal_title：Biometrics

authors： Salsburg D

更新日期：1986-09-01 00:00:00

abstract：:A nonparametric maximum likelihood procedure is given for estimating the survivor function from right-censored data. It approximates the hazard rate by a simple function such as a spline, with different approximations yielding different estimators. A special case is that proposed by Nelson (1969, Journal of Quality Te...

journal_title：Biometrics

authors： Whittemore AS,Keller JB

更新日期：1986-09-01 00:00:00

abstract：:Linear multivariate theory is applied to the problem of combining several multivariate bioassays. Results are an asymptotic test of the hypothesis of a common log relative potency; the maximum likelihood estimator of the common log relative potency; and an exact and asymptotic confidence interval estimator for log rel...

journal_title：Biometrics

authors： Meisner M,Kushner HB,Laska EM

更新日期：1986-06-01 00:00:00

abstract：:In this paper alternative methods for estimating the relative potency, its confidence intervals, and testing for proportionality are developed for multivariate bioassays. The test and estimate are based on the smaller characteristic root and the corresponding characteristic vector of a 2 X 2 matrix. The same idea is a...

journal_title：Biometrics

authors： Srivastava MS

更新日期：1986-03-01 00:00:00

abstract：:The "biometric school" founded by K. Pearson, F. Galton, and W. F. R. Weldon was concerned especially with heredity and variation, and between the wars "biometry" was not widely used as a general term for quantitative biology. The foundation of the Biometric Society encouraged this wider usage, and medical and biologi...

journal_title：Biometrics

authors： Armitage P

更新日期：1985-12-01 00:00:00

abstract：:The accuracy of a new diagnostic test is often determined by comparison with a reference test which also has unknown error rates. Maximum likelihood estimation of the error rates of both tests is possible if they are simultaneously applied to two populations with different disease prevalences. The estimation procedure...

journal_title：Biometrics

authors： Vacek PM

更新日期：1985-12-01 00:00:00

abstract：:A multiple toxicity model for the quantal response of organisms is constructed based on an existing bivariate theory. The main assumption is that the tolerances follow a multivariate normal distribution function. However, any monotone tolerance distribution can be applied by mapping the integration region in the n-dim...

journal_title：Biometrics

authors： Christensen ER,Chen CY

更新日期：1985-09-01 00:00:00

abstract：:Conventional statistical determinations of sample size in phase II studies typically lead to sample sizes of the order of 25 (Schoenfeld, 1980, International Journal of Radiation Oncology, Biology and Physics 6, 371-374). When the development of new treatments is proceeding rapidly relative to the recruitment of suita...

journal_title：Biometrics

authors： Whitehead J

更新日期：1985-06-01 00:00:00

abstract：:In a study designed to assess the relationship between a dichotomous exposure and the eventual occurrence of a dichotomous outcome, frequency matching has been proposed as a way to balance the exposure cohorts with respect to the sampling distribution of potential confounding factors. This paper discusses the pooled e...

journal_title：Biometrics

authors： Weinberg CR

更新日期：1985-03-01 00:00:00

abstract：:A procedure is given for estimating the ratio of the means of two populations using the data from two independent random samples when the observations are normally distributed with population variances that are related to the population means. ...

journal_title：Biometrics

authors： Cox CP

更新日期：1985-03-01 00:00:00

abstract：:Suppose that a heterogeneous group of individuals is followed over time and that each individual can be in state 0 or state 1 at each time point. The sequence of states is assumed to follow a binary Markov chain. In this paper we model the transition probabilities for the 0 to 0 and 1 to 0 transitions by two logistic ...

journal_title：Biometrics

authors： Muenz LR,Rubinstein LV

更新日期：1985-03-01 00:00:00

abstract：:For patients with chronic myelogenous leukemia (CML), the effect of elevated blood levels of adenosine deaminase (ADA) is studied as a marker for transitions from stable disease to blast crisis and then to death. Data in the form of snapshots over time, with day, state of disease, and ADA level, are analyzed for 55 pa...

journal_title：Biometrics

authors： Klein JP,Klotz JH,Grever MR

更新日期：1984-12-01 00:00:00

abstract：:Bayesian methods are presented for assessing bioequivalence for studies in which a new formulation and a standard are administered simultaneously, and for Latin square designs which compare two or more new formulations to a standard. Two examples illustrate the application of the methods. ...

journal_title：Biometrics

authors： Selwyn MR,Hall NR

更新日期：1984-12-01 00:00:00

abstract：:Five procedures are considered for the comparison of two or more multivariate samples. These procedures include a newly proposed nonparametric rank-sum test and a generalized least squares test. Also considered are the following tests: ordinary least squares, Hotelling's T2, and a Bonferroni per-experiment error-rate ...

journal_title：Biometrics

authors： O'Brien PC

更新日期：1984-12-01 00:00:00

abstract：:Heart rate oscillates in synchrony with respiration. Several methods have been employed to assess this 'sinus arrhythmia', as an index of autonomic nervous system function. This paper proposes a new, easily computed measure, R, which is relatively resistant to the major nonrespiratory sources of variation, including p...

journal_title：Biometrics

authors： Weinberg CR,Pfeifer MA

更新日期：1984-09-01 00:00:00

abstract：:The aim of this study is to estimate incidence rates of onchocerciasis from skin-snip biopsies, based on incomplete data obtained in field surveys, with consideration of false negatives. The method of maximum likelihood is employed and the effect of false negatives on the incidence rates is discussed. ...

journal_title：Biometrics

authors： Yanagawa T,Kasagi F,Yoshimura T

更新日期：1984-06-01 00:00:00

abstract：:The estimation of gene frequencies, linkage disequilibrium and disease associations for the human leukocyte antigen (HLA) system is considered. Comprehensive models for HLA data are introduced and contrasted with simpler approaches to the analysis of such data. ...

journal_title：Biometrics

authors： Farewell VT,Dahlberg S

更新日期：1984-06-01 00:00:00

abstract：:The use of three periods in the two-treatment crossover design for clinical trials is considered. It is proposed that a series of such trials in a particular therapeutic area may establish the relevance of the crossover design in that area. Treatment sequences to be used in three-period two-treatment trials are discus...

journal_title：Biometrics

authors： Ebbutt AF

更新日期：1984-03-01 00:00:00

abstract：:A general formula for the frequency of different recombinant gamete types, in terms of the underlying distribution of crossovers, is derived. This formula may be applied to any theoretical model of recombination in which it is assumed that there is no chromatid interference. Multiple-locus recombination data may be ev...

journal_title：Biometrics

authors： Risch N,Lange K

更新日期：1983-12-01 00:00:00

abstract：:A method is proposed for calculating the probabilities of assignment of a patient to treatments; it involves minimizing a quadratic criterion subject to a balance constraint. The optimal probabilities are very easy to compute. Numerical illustration is given and comparisons are drawn with the entropy-based methods of ...

journal_title：Biometrics

authors： Titterington DM

更新日期：1983-12-01 00:00:00

abstract：:In the area of ecological research the study of species diversity of a community or population seems to have been fully developed. However, the problem of how the distributions and expectations of the sample diversity indices are affected by the population diversity has received little attention. In this paper we show...

journal_title：Biometrics

authors： Tong YL

更新日期：1983-12-01 00:00:00

abstract：:In an epidemiological study of risk factors in breast cancer, data are available on confirmed cases from a diagnostic clinic and on controls from a screening clinic that sampled the general population. Relative risk estimation is complicated by differences in the interviewing environment and in the wording and order o...

journal_title：Biometrics

authors： Elton RA,Duffy SW

更新日期：1983-09-01 00:00:00

abstract：:Computer simulation has been used to compare four methods for calculating confidence intervals for simple rate ratios estimated from cohort studies. The method proposed by Cornfield (1956. In Proceedings of the Third Berkeley Symposium on Mathematical Statistics and Probability. Vol. IV, 135-148) for interval estimati...

journal_title：Biometrics

authors： Howe GR

更新日期：1983-06-01 00:00:00

abstract：:A formula is derived for determining the number of observations necessary to test the equality of two survival distributions when concomitant information is incorporated. This formula should be useful in designing clinical trials with a heterogeneous patient population. Schoenfeld (1981, Biometrika 68, 316-319) derive...

journal_title：Biometrics

authors： Schoenfeld DA

更新日期：1983-06-01 00:00:00

abstract：:At any age the mean residual life function gives the expected remaining life at that age. Reliabilists and biometricians have found it useful to categorize failure distributions by the monotonicity properties of the mean residual life function. Hollander and Proschan (1975, Biometrika 62, 585-593) have derived tests o...

journal_title：Biometrics

authors： Chen YY,Hollander M,Langberg NA

更新日期：1983-03-01 00:00:00

abstract：:A topic of current biometric discussion is whether stratification should be used in randomized clinical trials and, if so, which kind. An approach based upon randomization theory is used to evaluate pre- versus post-stratification. The results obtained relate specifically to the effect of the size of the clinical tria...

journal_title：Biometrics

authors： McHugh R,Matts J

更新日期：1983-03-01 00:00:00

abstract：:The basic problem under consideration is the comparison of treatments with respect to a response Y when a covariable X is taken into account. Various methods involving matching may be regarded as compromises between the standard analysis of covariance and the standard analysis of independent matched pairs. First, ther...

journal_title：Biometrics

authors： Quade D

更新日期：1982-09-01 00:00:00

abstract：:For the same number of observations in a small-sample clinical trial with dichotomous outcome, the statistical power associated with a two-sample design, analyzed by Fisher's exact test, is slightly greater than that associated with a matched design, analyzed by McNemar's test, and hence of the matched design, is mono...

journal_title：Biometrics

authors： Wacholder S,Weinberg CR

更新日期：1982-09-01 00:00:00

abstract：:The risks of conception, due to sexual intercourse at various times before and after the periovulatory rise in the woman's basal body temperature, are evaluated. In general, the risk is small nine or more days before, and two or more days after, the first day of elevated temperature. The model for the conception proba...

journal_title：Biometrics

authors： Royston JP

更新日期：1982-06-01 00:00:00

abstract：:Epidemiolgic studies have strongly suggested that a vast majority (80-90%) of cancers are caused by radiation, chemical and biologic agents; the remainder result from endogenous or genetic factors. Biologically, cancer is most probably the end result of a complex multistage process and therefore may be due to a sequen...

journal_title：Biometrics

authors： Lilienfeld AM

更新日期：1982-03-01 00:00:00

abstract：:If the regulatory requirements are symmetrical, the use of symmetrical confidence intervals as a decision rule for bioequivalence assessment leads, as shown by simulations, to better level properties and an inferior power compared to a rule based on shortest confidence intervals. A choice between these two approaches ...

journal_title：Biometrics

authors： Mandallaz D,Mau J

更新日期：1981-06-01 00:00:00

abstract：:The Colton model for the choice between two medical treatments is studied, with the additional assumption that there is a time lag between the administration of the treatments and the availability of the responses. Two simple procedures are suggested for dealing with patients who arrive during the waiting period, caus...

journal_title：Biometrics

authors： Langenberg P,Srinivasan R

更新日期：1981-03-01 00:00:00