bluuebunny/crossref_metadata_2025_split huggingface dataset:
Response Curve Comparison by Pseudo‐Multivariate Two‐Sample Configural Frequency Analysis
Authors: Krebs Harald , Ising Marcus , Janke Wilhelm , Macht Michael , von Eye Alexander , Weijers Heinz‐Gerd , Weyers Peter 
Published: May 2007

AbstractThis paper introduces pseudo‐multivariate Configural Frequency Analysis (CFA) for comparison of time series from two independent samples. The method extends application of standard two‐sample CFA, bi‐prediction CFA, and longitudinal CFA. Methods for identification of uni‐discrimination types and bi‐discrimination types are proposed. The pseudo‐multivariate CFA is applied to sets of response curves from two independent samples of rats. The experimental group of rats was exposed to a stressful noise condition. The control group was not exposed to stress. Amount of food intake was measured over five days. Longitudinal discrimination types suggest that, under stress, rats reduce food intake at first, increase intake as habituation to stress increases, and show greater day‐to‐day variability of intake.
Prediction of Response to Selection and Inbreeding Coefficient under Assortative Mating
Authors: Nomura T. 
Published: May 2007

AbstractA method for predicting response to selection and inbreeding coefficient under the continuous use of assortative mating was derived. Using the method, numerical computation was carried out, and the utility of assortative mating in the selection programmes was evaluated. It was shown that the continuous use of assortative mating could not produce an appreciable additional increase in intermediate‐ or long‐term selection response.
Estimation of Differences and Ratios of Average Age at First Occurrence
Authors: Boshuizen Hendriek C. , Greenland Sander 
Published: May 2007

AbstractAverage age at first occurrence of a disease is easier to interpret than the incidence rate, which can be difficult to interpret for a common disease. Basic methods for estimating univariate differences and ratios for average age at first occurrence are outlined and illustrated with a real‐life example.
An Application of Renewal Theory to Contraceptive Follow‐up Studies, Exemplified by an Intrauterine Device Study
Authors: Liu Peng T. , Chow Lien P. 
Published: May 2007

AbstractContraceptive practice consists of a series of recurrent events of use and nonuse. Application of the life table technique for analysis of multiple‐segment contraceptive usage is not entirely satisfactory. In this paper the renewal process approach is applied to the results of contraceptive follow‐up studies involving all segments of use. By means of this model, it is possible to estimate the proportion of current users, the average duration of actual use, and the average number of segments used by the acceptors. The practical importance of these parameters for the evaluation of family planning programs is considered.
A Monte Carlo Test for Variance Homogeneity in Linear Models
Authors: Piepho Hans‐Peter 
Published: May 2007

AbstractA Monte Carlo procedure is proposed for testing homogeneity of variances in linear models. The method is applicable to a variety of common experimental designs. It is valid when errors are independently normally distributed. Under nonnormality the test is expected to behave robust in a similar fashion as Levene's test. Three examples are given to demonstrate the method.
A Confidence Region Approach for Assessing Equivalence in Variability of Bioavailability
Authors: Chen Keh‐Wei , Li Gang , Sun Yanging , Chow Shein‐Chung 
Published: May 2007

AbstractThe problem for assessment of equivalence in variability of bioavailability between two drug products is considered. Similar to the method for assessing bioequivalence in average bioavailability proposed by Chow and Shao (1990), an exact confidence region approach is derived when the intersubject variance is known. When the intersubject variance is unknown, a large sample approximation is considered. The proposed method for assessing equivalence of variability of bioavailability appears to be asymptotically uncorrelated with that of Chow and Shao (1990) for average bioavailability. As a result, the proposed method in conjunction with the method proposed by Chow and Shao (1990) constitutes a confidence region approach for assessing population bioequivalence. An example concerning a bioequivalence trial with 24 healthy volunteers is provided to illustrate the proposed method.
Confidence Intervals for Microbial Density Using Serial Dilutions with MPN Estimates
Authors: Garthright Wallace E. , Blodgett Robert J. 
Published: May 2007

AbstractAn alteration to Woodward's methods is recommended for deriving a 1 — α confidence interval for microbial density using serial dilutions with most‐probable‐number (MPN) estimates. Outcomes of the serial dilution test are ordered by their MPNs. A lower limit for the confidence interval corresponding to an outcome y is the density for which y and all higher ordered outcomes have total probability α/2. An upper limit is derived in the analogous way. An alteration increases the lowest lower limits and decreases the highest upper limits. For comparison, a method that is optimal in the sense of null hypothesis rejection is described. This method ranks outcomes dependent upon the microbial density in question, using proportional first derivatives of the probabilities. These and currently used methods are compared. The recommended method is shown to be more desirable in certain respects, although resulting in slightly wider confidence intervals than De Man's (1983) method.
Dependence Functions and Frailties
Authors: Oluyede Broderick O. 
Published: May 2007

AbstractThis note considers association between nonnegative random variables in which the two observed survival times depend on an unobservable random variable via the proportional hazard model. When the random variables are subject to censoring, the conditional hazard functions provides a reasonable means of describing the association between the two variables. A numerical example demonstrating association in disease incidence in ordered pairs of individuals is analysed. Also, examples of distributions satisfying the notions of dependence considered are provided.
On Indifference Zone Selection with a Preference Threshold
Authors: Coolen F. P. A. , van der Laan P. 
Published: May 2007

AbstractThis paper discusses a selection criterion that generalizes the well‐known concept of indifference zone selection through a preference threshold. A population is preferred to another population if the difference in the sums of observed values exceeds a given nonnegative threshold value. We present an argument for this selection rule by modelling preference by imprecise previsions. We aim at guidelines to design a selection experiment, which is characterized by two numbers: the number of necessary observations per population, and the preference threshold. Next to the probability of correct selection we also need a second specification. In this paper we consider a probability of false selection that is strongly related to the minimum probability of correct selection. Based on this model the outcome of an experiment may be ‘no selection’, at least not based on strong preference of a single population. The ideas are presented through a simple selection problem for normal populations with common known variance. Although the theory has a frequentist nature, the derivation and justification of the selection rule through imprecise previsions relies on Bayesian foundations, and via this route we gain more insight into the selection criterion.
Initial Value Dependence: A Comparison of Two Methods For Its Study
Authors: Raykov Tenko , Penev Spiridon 
Published: May 2007

AbstractThis article is concerned with the comparison of slope estimator precision in regression analysis and the structural relationships approach (e.g., Humak, 1983, ch. 3; Kendall and Stuart, 1977), as it is relevant for their applications when testing for initial value dependence in biomedical and behavioral contexts of repeated assessments (e.g., Blomqvist, 1977; Wall, 1977). As a basis for the comparison of the two methods, the mean square error is adopted. In the general case, it is argued for an informed (data‐dependent) choice between regression analysis and the structural relationships approach. For the apparent majority of biomedical and behavioral studies of the phenomenon of initial value depenence, this comparison suggests that structural relationships is the preferable approach leading to more trustworthy substantive conclusions.
A Note on Lancaster's Procedure for the Combination of Independent Events
Authors: Koziol James A. 
Published: May 2007

AbstractLancaster (1961) generalized Fisher's (1932) nonparametric procedure for combining independent p‐values by transforming Pi from the i‐th experiment to a chi‐squared random variable with di degrees of freedom, with di not necessarily equal to 2. We explore the relationship between Lancaster's procedure and a weighted Lipták procedure (Koziol and Tuckwell, 1994) under which Pi is transformed to the standard normal scale. We investigate approximations to the null distribution of Lancaster's test procedure, chi‐squared with d degrees of freedom. We find that the Cornish‐Fisher (1960) expansions and the Lugannani‐Rice (1980) saddlepoint approximations are quite accurate, for non‐integral values of d, and for values of d as low as 20.
Forecast of Sugarcane Yield Using Eye Estimate Alongwith Plant Characters
Authors: Agrawal Ranjana , Jain R. C. 
Published: May 2007

AbstractThe present study proposes to include farmers' appraisal (eye estimate) as one of the variables in the models alongwith plant characters. This will reduce the number of plant character in the model, thus reducing the cost on data collection. This has been demonstrated through regression and probability models.
On Choice of Subjects and Replicates in Estimating Among and Within Subject Variation
Authors: Wong Weng Kee , Lachenbruch Peter A. , Clements Philip J. 
Published: May 2007

AbstractWe consider the problem of choosing the number of replicates and number of subjects in a components of variance problem which optimizes various criteria. The case study here involves patients suffering from systemic sclerosis (Scleroderma), a form of rheumatic disease that is potentially disabling. Under the physical constraints imposed on the study, we find that using 2 or 3 replicates with as many patients as possible is the optimal strategy for several criteria.
Tests of Bivariate Symmetry with a One‐sided Alternative in the Analysis of Variance
Authors: Bhattacharya Bhaskar 
Published: May 2007

AbstractWe consider a two‐factor experiment in which the factors have the same number of levels with a natural ordering among levels. We test the hypothesis that the effects of the two treatments are symmetric against a one‐sided alternative using the likelihood ratio criteria. Test of the one‐sided alternative as a null hypothesis against no restriction has also been studied. Exact distribution theory under the null hypothesis is derived and is shown to be a weighted mixture of chi‐square distributions. An example is used to illustrate the procedure.
Pair Rank Set Sampling
Authors: Muttlak Hassen A. 
Published: May 2007

AbstractRanked set sampling (RSS) as suggested by McIntyre (1952) may be modified to introduced a new sampling method called pair rank set sampling (PRSS), which might be used in some area of application instead of the RSS to increase the efficiency of the estimators relative to the simple random sampling (SRS) method. Estimators of the population mean are considered. An example using real data is presented to illustrate computations.
A Matrix Formulation for Nonparametric Permutation Tests
Authors: Marcuson Richard 
Published: May 2007

AbstractMany of the common permutation tests, particularly those from survival analysis, are special cases of a more general methodology. They are based on a single covariance matrix which is simple and can be derived by elementary means. It is, however, surprisingly hard to find a complete treatment of this covariance matrix in the literature. Such a treatment is given here together with a discussion of the permutation tests' uses in data analysis.
Precision Intervals for Estimates of the Difference in Success Rates for Binary Random Variables Based on the Permutation Principle
Authors: Röhmel Joachim 
Published: May 2007

AbstractFisher's exact test is a very commonly applied test in clinical trials with a binary outcome variable (e.g. success/failure). However confidence statements about the difference of success rates are usually based on the normal approximation. This may sometimes lead to the confusing statement that the test is statistically significant at a prespecified level while the corresponding confidence interval includes the zero difference and vice versa. Here, we construct precision intervals for the difference of success rates from two independent samples based on the permutation principle which are in perfect agreement with the discrete (permutation) test and compare it to examples from the literature. APL programs are provided.
Catecholamine Response Curves of Male Hypertensives Identified by Lehmacher's Two Sample Configural Frequency Analysis
Authors: Müller Matthias J. , Netter Petra , Von Eye Alexander 
Published: May 2007

AbstractA new application of LEHMACHER'S (1980) marginal homogeneity sign tests is given by analysis of bivariate response curves (or response surfaces) in two unpaired samples of hypertensive versus normotensive patients. Rationale and computations are illustrated by empirical data from sympathomedullary stress research.
An Overview of Precedence‐Type Tests for Censored Data
Authors: Chakraborti S. , Van Der Laan P. 
Published: May 2007

AbstractPrecedence tests are simple yet robust nonparametric procedures useful for comparing two or more distributions. In this paper precedence‐type tests are considered when the data contain some censored observations. Generalizing the precedence statistic for uncensored data, the precedence tests for censored data are based on the Kaplan‐Meier estimators of the respective distribution functions and the corresponding quantile functions. The literature is reviewed for some two‐sample as well as some multi‐sample problems.
The Prior Distribution of the Minimum and Maximum Distance between Several Marker Loci and Quantitative Trait Loci
Authors: Teuscher F. , Tuchscherer A. 
Published: May 2007

AbstractIn order to control linkage experiments, exact formulas and approximations are derived for the minimum distance between quantitative trait loci and the nearest marker locus. The locations of the loci are assumed to be uniformly distributed over the genome. The locations of the marker loci may be known or unknown. The number and length of the chromosomes are arbitrary and therefore the results are applicable for all kinds of species. Analogous formulas are derived for the maximum distance between the quantitative trait loci and the nearest marker loci. For the probability of linkage more simple expressions are derived. The accuracy of the approximations is checked by a simulation.
Loglinear Symmetry and Quasi‐Symmetry Models for the Analysis of Change
Authors: Meiser Thorsten , Von Eye Alexander , Spiel Christiane 
Published: May 2007

AbstractLoglinear symmetry and quasi‐symmetry models are proposed as tools for investigating various hypotheses about change. First, a survey of model representations is provided, including model specification in terms of hierarchical loglinear models and in design matrix notation. Secondly, the range of symmetry and quasi‐symmetry models is extended to the joint analysis of several groups. Parameter constraints are discussed which allow one to test specific hypotheses about group differences in symmetric frequency distributions. Finally, symmetry and quasi‐symmetry models are considered for multiway contigency tables. In this context, loglinear total score models are proposed for the analysis of symmetry in several marginal distributions. The proposed models reflect cross‐sectional as well as longitudinal facets of development.
Likelihood‐Weighted Confidence Intervals for the Difference of Two Binomial Proportions
Authors: Lee J. Jack , Serachitopol Dan M. , Brown Barry W. 
Published: May 2007

AbstractTwo new methods for computing confidence intervals for the difference δ = p1 — p2 between two binomial proportions (p1, p2) are proposed. Both the Mid‐P and Max‐P likelihood weighted intervals are constructed by mapping the tail probabilities from the two‐dimensional (p1, p2)‐space into a one‐dimensional function of δ based on the likelihood weights. This procedure may be regarded as a natural extension of the CLOPPER‐PEARSON (1934) interval to the two‐sample case where the weighted tail probability is α/2 at each end on the δ scale. The probability computation is based on the exact distribution rather than a large sample approximation. Extensive computation was carried out to evaluate the coverage probability and expected width of the likelihood‐weighted intervals, and of several other methods. The likelihood‐weighted intervals compare very favorably with the standard asymptotic interval and with intervals proposed by HAUCK and ANDERSON (1986), COX and SNELL (1989), SANTNER and SNELL (1980), SANTNER and YAMAGAMI (1993), and PESKUN (1993). In particular, the Mid‐P likelihood‐weighted interval provides a good balance between accurate coverage probability and short interval width in both small and large samples. The Mid‐P interval is also comparable to COE and TAMHANE'S (1993) interval, which has the best performance in small samples.
Analysis of Randomized Dose‐Finding‐Studies: Closure Test Modifications Based on Multiple Contrast Tests
Authors: Hothorn L. A. , Neuhäuser M. , Koch H.‐F. 
Published: May 2007

AbstractThe power of single contrast tests strongly depends on the a priori unknown shape of the dose response relationship. Two approaches can be used to overcome this major disadvantage: the likelihood ratio test for order restriction or multiple contrast tests. Within the closure principle, the shape for the different hyptheses varies. Therefore multiple contrast tests are used as trend tests. Based on a simulation study the power advantage of this approach in comparison with single contrast tests is demonstrated.
Power of Some Tests for Umbrella Alternatives in the Multi‐Sample Location Problem
Authors: Büning Herbert , Kössler Wolfgang 
Published: May 2007

AbstractFor the c‐sample location problem with umbrella alternatives we present a modification of a test proposed by BARLOW et al. (1972) for trend alternatives. Furthermore, we study a rank version of this modified test following a proposal of CONOVER and IMAN (1981). These tests are compared with the test of MACK and WOLFE (1978) and with some so called Mack‐Wolfe‐type tests in which the Mann‐Whitney statistics are replaced by other two‐sample linear rank statistics. The comparison is referred to the power of the test assuming a broad range of distributions. It will be shown firstly, that for nonnormal data there are tests with higher power than the modification of the test of Barlow et al. and secondly, that for a special distribution there is a Mack‐Wolfe‐type test which is more efficient than is competitors. We also consider the case of unknown peak.
Almost Unbiased Ratio and Product Type Estimators: A New Approach
Authors: Mahajan P. K. , Singh Sarjinder 
Published: May 2007

AbstractIn this paper, we have proposed a new method, consisting of a linear variety of the estimators and a linear constraint to remove the bias appearing in the estimators of the ratio R = Y/X and product P = YX. The percent relative efficiency of proposed estimators has also been demonstrated with numerical illustrations.
A Kinetic Model for Human Platelet Survival with Long‐Lasting Time‐Activity Curves
Authors: Osterode Wolf , Rattay Frank 
Published: May 2007

AbstractA model is presented that allows for the interpretation of the time course of the level of radiolabeled platelets in terms of platelet survival times, rate constant for removal from circulation, pooling time in an extra pool, the rate at which platelets re‐enter circulation from the extra‐pool, and the size of the plasma pool and extra‐pools. The tenets of the model are that: (1) platelets leave the circulation at a rate proportional to their number per unit volume; (2) of the leaving platelets, a fraction b goes into a pool from which they return into circulation after a pooling time and another fraction (1 ‐ b) is irreversibly destroyed; (3) the platelets in the extra‐pool do not “queue up”, and thus the distribution function describing the probability of return is exponential; and (4) the time activity curve of the radiolabeled platelets can be described by the sum of two exponentials. Under steady state conditions, curve fitting allows determination of the constants determining the time activity curve (the respective amplitudes and rate constants of the two exponentials); mean pooling time; relative pool size; and survival time of platelets. The model is applied to data collected from patients over a period from 10 days following reinjection of autologous radiolabeled platelets.
Estimating the Order of a Sequence of Physiological Changes from Incomplete Data
Authors: Solow Andrew R. , Curran Mary Carla , Bentivegna Flegra 
Published: May 2007

AbstractThe problem considered in this paper is the estimation of the underlying order of m physiological changes from incomplete observations. The observations are incomplete in the sense that, for each individual in the sample, only the identity, but not the order, of the first k < m changes are observed, with k varying between individuals. An application to some data on physiological changes in fish undergoing sex change is presented.
Optimization of Dynamic Plant Nitrogen Uptake, Using Apriori Information of Plant Nitrogen Content
Authors: Vold A. , Sôreng J. S. 
Published: May 2007

AbstractEmphasizing that model development should be in accordance with the context under consideration, a model for plant nitrogen uptake is developed for use in connection with soil nitrogen models. The aim of the modeling is to improve the accuracy in model simulations of plant nitrogen uptake by application of optimization theory and apriori information of plant nitrogen content. A simple soil nitrogen model is coupled to the plant nitrogen uptake model, and solutions, obtained by two different methods, are presented. Suggestion for how to use the modeling principles in connection with a more complex plant nitrogen uptake model, and apriori information of plant dry weight, is given. It is believed that the modeling principles can also be used on other types of dynamic models with given apriori information.
A Game‐Theoretic Approach to Partitioning Attributable Risks in Epidemiology
Authors: Land Matthias , Gefeller Olaf 
Published: May 2007

AbstractThe concept of attributable risk has been developed to quantify that proportion of disease events in a population that can be ascribed to an exposure factor under study. Typically, several exposures have to be considered simultaneously in observational epidemiological studies when assessing their impact on the disease load. Whenever these exposures are subject of complex interactions the question arises, what contribution should be assigned to each of them. The paper points out that the epidemiological problem of finding “sensible” risk allocation methods can be formalized in a way that is equivalent to the game‐theoretic description of several players that act together in a grand coalition and are faced with the problem of dividing their profit “fairly” among them. The transfer of game‐theoretic results to epidemiology yields a unique method of allocating shares of the joint attributable risk, called partial attributable risks. To each exposure factor. Application and justification of the method are illustrated using data from the G.R.I.P.‐study (Göttinger Risiko‐, Inzidenz‐ und Prävalenzstudie).