bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Properties of Cell Kinetics Indicators. A Computer Simulation Study
Authors: Zorin A. V. , Yakovlev A. Yu. 
Published: May 2007

AbstractThe results of studying the properties of cell kinetics indicators by computer simulation methods are reported. Two problems are considered, one concerning investigation into the efficiency and robustness of the procedure earlier proposed by us (YAKOVLEV et al., 1977) for estimating the so‐called q‐index which characterizes the integral flow of cells into a given mitotic cycle phase. The other problem is substantiation of the way to form mathematical expectations of the indices of cell cycle phases. Discussion of the results of simulation experiments is preceded by analytical solutions of some of the simpler cases of such problems with the use of the theory of multitype age‐dependent branching stochastic processes.
The Structure of Ellipsoidal Distributions, II. Principal Components
Authors: Jensen D. R. 
Published: May 2007

AbstractPrincipal‐axis rotations are informative for data from ellipsoidal distributions even without moments. The standard normal‐theory tests used in principal components analysis are shown to be identical in level and power for all ellipsoidal distributions under a specified model for sampling. This follows from basic invariance properties of distributions associated with sample dispersion matrices. Similar findings are reported for HOTELLING'S (1936) canonical analysis in Part I of this study.AMS 1980 subject classification. Primary 62 H 25; Secondary 62 H 05.
Four Kinds of Symmetry Models and their Decompositions in a Square Contingency Table with Ordered Categories
Authors: Tomizawa S. 
Published: May 2007

AbstractIn a square contingency table four kinds of symmetry models are proposed and their decompositions are given. Two models of them are extensions of the local point‐symmetry model and the reverse local point‐symmetry model by TOMIZAWA (1985), and the other two models are concerned with the inclined point‐symmetry model by TOMIZAWA (1986) and the conditional symmetry model by MCCULLAGH (1978). An example is given.
P‐values For Discrete Test Statistics
Authors: Franck W. E. 
Published: May 2007

AbstractThis paper considered the relative merits of the P‐value and the mid‐P‐value. It is shown that inference based on the mid‐P‐value is in a certain sense on firmer ground. In particular the expected mid‐P‐value does not change under an irrelevant breakup in the test statistic.
A Modified Exact Test for 2 × 2 Contingency Tables
Authors: Haber M. 
Published: May 2007

AbstractA modified exact test is proposed for 2×2 contingency tables. This test, which is based on a less conservative definition of the concept of significance (STONE, 1969) is compared with a modified form of Pearson's X2 test and with Tocher's randomized exact (UMPU) test. The sizes of the new test lie near the nominal 0.05 levels while those of the X2 test usually exceed the nominal level, sometimes by a factor of 2 or more. The power of the modified test is usually close to that of the UMPU test.
A Note on a Continuity Correction for Testing in Three‐Dimensional Configural Frequency Analysis
Authors: Küchenhoff H. 
Published: May 2007

AbstractA continuity correction is proposed for the test statistics of HABERMAN (1978) and LEHMACHER (1981) for identifying overfrequented (or underfrequented) cells in the three‐dimensional Configural Frequency Analysis (CFA). Its quality is shown by comparison with the test based on the exact distribution of the cell frequencies.
Model‐Based Statistical Procedures for the Analysis of in Vitro Mutagenesis Assays
Authors: Kaldor John 
Published: May 2007

AbstractA number of short‐term screening assays for potential chemical carcinogens and mutagens involve the measurement of mutation rates inin vitrocell populations. In this paper, statistical procedures are proposed for the analysis of results from these assays. The procedures, which are based on previously developed stochastic models of cell growth and mutation, include hypothesis tests for the comparison of mutation rates in treated and control cultures, and estimation and hypothesis tests for the parameters of a linear mutagenesis dose‐response. Computer simulation is used to validate the methods, and they are illustrated by an analysis of data obtained under the mouse lymphoma mutagenesis protocol.
General Derivation of Intraclass Correlation Coefficients
Authors: Schemper M. 
Published: May 2007

AbstractA general intraclass correlation coefficient is derived similarly to the general correlation coefficient given by KENDALL (1962). This coefficient II embraces as specific cases three intraclass correlations, related to Pearson's r, Kendall's tau and Spearman's rs, that were dealt with by FISHER (1921), WHITFIELD (1949), SHIRAHATA (1981) and SCHEMPER (1984). Formal relationships are presented and the qualification of the three coefficients for specific applications is discussed.
A Comparison Between Several Goodness of Fit Tests for Cox's Model
Authors: Nagelkerke N. J. D. , Oosting J. , Hart A. A. M. 
Published: May 2007

AbstractA comparison is made between two approaches to testing goodness of fit of Cox's regression model for survival data. The first approach is based on the inclusion of time dependent covariates, whereas the second one is based on the autocovariance of successive contributions to the derivative of the loglikelihood. It appears that the second test is most appropriate for testing in situations where the structure of the departure from proportional hazards is not known a priori. An approximate expression for the relative efficiency of the two test procedures is presented.
A Power Law Model for Survival Data Using GLIM
Authors: Wu Shu‐Chen Ho , Fung Karen Yuen 
Published: May 2007

AbstractThis paper proposes a regression model for the Weibull survival distribution of which the scale parameter is a power function of covariates. The estimation of parameters for partially censored data is pursued by using a statistical package called GLIM. Two sets of carcinogenic data are used to illustrate this procedure.
Yule‐Coefficients for Second‐ and Higher‐Order Associations
Authors: Lienert G. A. , von Eye A. 
Published: May 2007

AbstractThe well‐known Q coefficient of association defined by YULE (1900) for two attributes is generalized from first‐order association Q to second‐order association Q for three attributes and to higher‐order Q's for more than three attributes (or binary variables). Q analysis of t binary variables is shown to be a suitable means for describing simple (quasi‐parametric) or complex (multi‐nonparametric) relationships in a t‐dimensional contingency cube. A biometrical example is given using clinical data.
Some Methods for Summarizing Survivorship Data in Nonstandard Situations
Authors: Gore A. P. , Paranjape Sharayu , Rajarshi M. B. , Gadgil Madhav 
Published: May 2007

AbstractOne difficulty in summarising biological survivorship data is that the hazard rates are often neither constant nor increasing with time or decreasing with time in the entire life span. The promising Weibull model does not work here. The paper demonstrates how bath tub shaped quadratic models may be used in such a case. Further, sometimes due to a paucity of data actual lifetimes are not as certainable. It is shown how a concept from queuing theory namely first in first out (FIFO) can be profitably used here. Another nonstandard situation considered is one in which lifespan of the individual entity is too long compared to duration of the experiment. This situation is dealt with, by using ancilliary information. In each case the methodology is illustrated with numerical examples.
Tables and Procedures for the Determination of Power and Sample Sizes in Univariate and Multivariate Analyses of Variance and Regression
Authors: Hager W. , Möller H. 
Published: May 2007

AbstractThe available power tables for use in experimental design only serve for limited practical purposes, since they are restricted to very few levels of significance such as .01, .05, and .10. With these values, however, usually no correction for cumulating error probabilities, for example, by the Dunn‐Bonferroni method, can be achieved, because (very) low values of a and sometimes even of α are necessary. Therefore, power tables are presented that encompass a wide range of different values for a (.0005 to .40), for power (.50 to .9995), and for 45 different values of the degrees of freedom for the numerator of the F ratio (u = 1 to 150). Four of the 16 tables are printed. Their use is demonstrated for some paradigmatic problems in univariate and multivariate analyses of variance and regression.
A Likelihood Ratio Test of the Equality of Paired Survival Data with Censoring
Authors: Knapp R. G. , Gross A. J. , Cantor A. B. 
Published: May 2007

AbstractA test is developed to determine whether the mean survival times are equal when dealing with paired survival data.We assume the data follow a bivariate exponential distribution for which the variables are conditionally independent. The unconditional distribution is derived in which the distribution of the nuissance variable is general.A method based on the likelihood ratio is derived to obtain the test. The data are allowed to have both left and right censoring.
Randomization Tests for Censored Survival Distributions
Authors: Edgington E. S. , Gore A. P. 
Published: May 2007

AbstractThis paper discusses the application of randomization tests to censored survival distributions. The three types of censoring considered are those designated by MILLER (1981) as Type 1 (fixed time termination), Type 2 (termination of experiment at r‐th failure), and random censoring. Examples utilize the Gehan scoring procedure. Randomization tests for which computer programs already exist can be applied to a variety of experimental designs, regardless of the presence of censored observations.
The Performance of Goodness of Fit Tests for Logistic Regression with Discrete Covariates
Authors: Korn L. R. , Hosmer D. W. , Lemeshow S. 
Published: May 2007

AbstractThis paper considers the distribution of previously proposed goodness of fit tests when some or all of the covariates are dichotomous variables. The simulations show that of the statistics suggested for testing fit only one appears suitable for use with discrete covariates. This statistic uses conditional maximum likelihood estimates and groups the estimated probabilities into groups of equal size or into groups based on the patterns of the covariates when these are few in number.
Closed Form Estimators of Latent Cell Frequencies
Authors: Bonett D. G. , Woodward J. A. , Bentler P. M. 
Published: May 2007

AbstractOne‐stage and two‐stage closed form estimators of latent cell frequencies in multidimensional contingency tables are derived from the weighted least squares criterion. The first stage estimator is asymptotically equivalent to the conditional maximum likelihood estimator and does not necessarily have minimum asymptotic variance. The second stage estimator does have minimum asymptotic variance relative to any other existing estimator. The closed form estimators are defined for any number of latent cells in contingency tables of any order under exact general linear constraints on the logarithms of the nonlatent and latent cell frequencies.
The Statistical Properties of Genetic Absolute Distance
Authors: Katz M. , Goux J.‐M. 
Published: May 2007

AbstractThe statistical properties of one estimator of absolute genetic distance (1/2) K∑i=1 |pxi‐yr|, tween two populations X and Y, are presented. It is shown that using this distance in small samples can be misleading particularly when populations are close to each other.
Equidirection: A Measure of Similarity Among Time Series
Authors: Yassouridis A. , Hansert E. 
Published: May 2007

AbstractIn the present paper we investigate the concept of equidirection, i.e. similarity in the direction of variation, or parallelism in the broader sense, among m (m ≧ 2) times series, especially under the assumption that the time series are realizations of processes with independent increments. However, the processes need not be stationary. Furthermore, the probabilities for the direction of variation may be unstable, in which case only upper and lower bounds are known. A measure based on the concept of equidirection was developed that enables identification of clusters of similar time series and analysis of relationships among variables.
Linear Predictivity: An Alternative for MANOVA and Multivariate Multiple Regression
Authors: Lefkovitch L. P. 
Published: May 2007

AbstractThe maximal linear predictable combination of a set of dependent variables is defined as that linear combination maximizing the multiple correlation coefficient with the predictor set. It allows the relative importance of a number of factors to be evaluated for the joint response, rather than for the response of each dependent variable in turn. The procedure is illustrated by an example.AMS subject classification: major 62J10, 62H20; minor 62H25.
Harmonic Mean Approach to Regression Analysis Under Heteroscedasticity and Nonnormality
Authors: Tabatabai M. A. , Tan W. Y. 
Published: May 2007

AbstractIn this paper, by combining the harmonic mean approach with the Welch and the James procedure (see WELCH 1951, JAMES, 1951), we develop some robust procedures for testing parallelism in several straight lines under heteroscedasticity and nonnormality. Through Monte Carlo simulations it is shown that these new tests are quite robust with respect to departure from normality. For small sample sizes, however, the TAN‐TABATABAI (1984) Fβ and F*β tests appear to be more powerful than the new tests, although when sample sizes are not small, there are hardly any differences between the Tan‐Tabatabai Fβ and F*β tests and the new tests.
The Relative Power of Two Asymptotic Multivariate Tests for Homogeneity in a Contingency Table
Authors: Onukogu Ike B. 
Published: May 2007

AbstractIn a three way contingency table two multivariate tests for homogeneity have been proposed by the author (1983) a the “catanova” test, which is a trace “metric” test and b the “multinova” test which is determinant based. Both tests are asymptotically distributed as chi‐square.In this paper, the power values of the tests are compared and conditions are given for preference of each test.
On Combining Estimates of Relative Risk Using the Negative Binomial Mode
Authors: Bennett B. M. 
Published: May 2007

AbstractThe negative binomial distribution (N.B.) was previously proposed (BENNETT, 1981) in the estimation of and tests of significance for the relative risk (ψ) in prospective studies in epidemiology. This paper discusses the application of the N.B. model in combining estimates of ψ from a series of prospective studies and in statistical tests of the equality of these estimates.
The Point Evaluation Method for Approximating Function Means, Variances and Covariances
Authors: Manly B. F. J. 
Published: May 2007

AbstractA perennial problem in statistics is the determination of biases, variances and covariances for functions of random variables X1, X2, …, Xn which themselves have a known distribution. A common approach is through equations based upon Taylor series approximations but a “point evaluation” method may sometimes be a useful alternative. This involves approximating the multivariate distribution of the X variables by the 2n points given by X1=μ1±1, X2 = μ2 ±2, …, Xn = = μn μn, where μi is the mean and σi the standard deviation of Xi, with appropriate point weights. An advantage over the Taylor series approach is that function derivatives do not have to be explicitely calculated. The point evaluation method is particularly useful in cases where the X variables are uncorrelated. Then the evaluation of the 2n points can be replaced by the evaluation of 2n points. The point evaluation method is illustrated with powers of a normally distributed variable, and with estimation of gene frequencies from ABO blood group frequencies.
A General Statistical Model for Multifactorial Inheritance of Discontinuous Traits
Authors: Bonet D. G. , Smalley Susan I. , Woodward J. A. 
Published: May 2007

AbstractA general statistical model for the analysis of ordered discrete phenotypes given a multifactorial mode of inheritance is outlined. This model can be applied to give (i) components of variance and covariance for various genetic and environmental effects that are eatimable from the genetic sampling design, (ii) a factor analysis structure, and (iii) regression estimates for description of the relationship among the genetic and environmental factors.
Parent/offspring Relations for a Fitness Related Character
Authors: Skovgaard I. M. 
Published: May 2007

AbstractSome parent/offspring relations of a quantitative character are discussed, in particular in relation to the mean change from one generation to the next. It is shown that the prediction of this “progress” as the heritability multiplied by the selection differential takes only the slope of the parent/offspring relation into account and holds if, and only if, the population mean is a fixpoint of the mid‐parent/offspring regression in the case of a character that is unrelated to sex. In particular, two examples show that this may not be the case if the character is related to fitness by pleiotropic effects of single genes.
An Evaluation of Different Methods in Epidemiologic Studies of Radiation Risks
Authors: Schindel F. 
Published: May 2007

AbstractThe probability of detecting possible late effects of ionizing radiation in human populations depends on the size of exposure in the study population and on the epidemiologic evaluation method used. This is not only due to the mathematical or statistical properties of the method, but also to the choice of the control population, which may be either external (usually large) or internal (usually not so large). Moreover, the use of a large external control population often results in an increasing influence of selection factors expressing themselves e.g. through the ‘healthy worker’ effect. In this paper three different methods usually employed in follow‐up studies are reviewed: the calculation of Standardized Mortality Ratios (SMR), a contingency table analysis based on Person‐Years (PY) and the comparison of Cumulative Mean Doses (CMD) within different subcohorts. The methods are illustrated with a simple radiation risk model; nevertheless, most of the conclusions apply to non‐radiation risk studies as well. The CMD‐method is shown to be heavily selection sensitive.
Iso‐ and Anisoasymmetry Testing in Pre‐post Rating Designs
Authors: Heilmann W.‐R. , Lienert G. A. 
Published: May 2007

AbstractIt is suggested to test against anisoasymmetry rather than against marginal homogeneity if (1) a pre‐post treatment matched pairs contingency table is ordinally scaled by clinical ratings and if (2) the alternative to marginal homogeneity is a shift in location from pre‐ to post treatment ratings. Testing against anisoasymmetry may detect treatment effects which are not manifest in marginal inhomogeneities.
Investigations on Some Attributes of the Likelihood Function for MPN Determination
Authors: Diener W. 
Published: May 2007

AbstractThe paper investigates the likelihood function to determine the MPN (Most Probable Number as a measure of concentration in the virology), dependent on several parameters. Taking only ‘probable’ result schemes into the MPN‐tables they would become much shorter. There are suggested two conditions for the selection of the result schemes, given and compared by some tables together with a mathematical foundation of the number of the selected schemes. Some tables and a theorem about success probabilities of the result schemes point out their changes under different conditions (number of tubes, number of dilutions, dilution ratio), and make it possible to estimate success probabilities of result schemes not selected by the more restricted condition.
Estimation of Individual Growth Curves by Empirically Weighted Least Squares
Authors: Louv W. C. 
Published: May 2007

AbstractThe simultaneous estimation of individual growth curves and a mean growth curve is accomplished by weighted least squares. A polynomial curve is fitted for each individual and the polynomial parameters are linear functions of parameters corresponding to covariates. A simple, computationally efficient variance‐covariance estimator is derived. The resultant estimate is used in the weighted least squares estimation. The results are compared to empirical Bayes estimation.
On Testing a Trend in Means in Oneway Layout
Authors: Le Chap T. 
Published: May 2007

AbstractA test for a trend in means in oneway layout is discussed with particular emphasis on sample size determination. The proposed method amounts to formulating a linear contrast among sample means and testing it for significance. The resulting test statistic is reduced to a test by Barlow et al. (1972) When sample sizes are equal and to the Armitage‐Kendall correlation test for a trend in proportions when the response variable is dichotomous. The problem of sample size determination is discussed and illustrated with numerical examples.
Log‐linear Models in a Study of Gall Bladder Disease
Authors: Janardan K. G. , Pandarinath S. 
Published: May 2007

AbstractBiliary drainage and X‐rays have been used singly and together in the diagnosis of gall bladder disease. Data from two sets of patients were statistically analyzed using log‐linear analysis of contingency tables. The results of the study show that “biliary drainage” is dependent of “X‐ray” and “Pathology”; abnormal X‐ray is associated with abnormal pathology. Thus, biliary drainage is not of such value as to base surgery on it alone. However, X‐rays are of significant value in the diagnosis of the gall bladder disease and to decide whether a surgery is needed or not.
Maximum Likelihood Estimation of Genetic Parameters in Cell Populations
Authors: Tan W. Y. , Tou Conrad 
Published: May 2007

AbstractIn this paper we consider a cell population such as bacteria consisting of two types of cells, mutant and nonmutant. Under the mutation and homogeneous pure birth processes, this paper derives a maximum likelihood estimation procedure for estimating mutation rate and birth rate. The method is applied to Newcombe's data; further some Monte Carlo studies are generated. The numerical results indicate that the method is quite efficient for estimating genetic parameters in cell populations.
Probability of Inadmissible Estimates of Heritability from Regression and Half‐sib Analyses
Authors: Prabhakaran V. T. , Jain J. P. 
Published: May 2007

AbstractFormulae are derived for the probability of obtaining inadmissible estimates of heritability (h2) in half‐sib and intra‐sire regression analyses, under the additive‐dominance‐epistasis model of gene action. Results for several combinations of sire/dam number, h2 and the proportion of additive x additive epistasis are given for the balanced situation.
Test Procedures in Configural Frequency Analysis (CFA) Controlling the Local and Multiple Level
Authors: Perli H.‐G. , Hommel G. , Lehmacher W. 
Published: May 2007

AbstractThe test statistics used until now in the CFA have been developed under the assumption of the overall hypothesis of total independence. Therefore, the multiple test procedures based on these statistics are really only different tests of the overall hypothesis. If one likes to test a special cell hypothesis, one should only assume that this hypothesis is true and not the whole overall hypothesis. Such cell tests can then be used as elements of a multiple test procedure.In this paper it is shown that the usual test procedures can be very anticonservative (except of the two‐dimensional, and, for some procedures, the three‐dimensional case), and corrected test procedures are developed. Furthermore, for the construction of multiple tests controlling the multiple level, modifications of Holm's (1979) procedure are proposed which lead to sharper results than his general procedure and can also be performed very easily.