Phase II trial design with growth modulation index as the primary endpoint

Molecularly targeted, genomic‐driven, and immunotherapy‐based clinical trials continue to be advanced for the treatment of relapse or refractory cancer patients, where the growth modulation index (GMI) is often considered a primary endpoint of treatment efficacy. However, there little literature is available that considers the trial design with GMI as the primary endpoint. In this article, we derived a sample size formula for the score test under a log‐linear model of the GMI. Study designs using the derived sample size formula are illustrated under a bivariate exponential model, the Weibull frailty model, and the generalized treatment effect size. The proposed designs provide sound statistical methods for a single‐arm phase II trial with GMI as the primary endpoint.     

Analysis of pseudo-panel data with dependent samples

In this paper, we discuss a model for pseudo-panel data when some but not all of the individuals stay in the sample for more than one period. We use data on the labor market of the Basque Country from 1993 to 1999 treated through FORTRAN 77 programing. We construct economically reasonable age cohorts for active population and use gender, qualification and social status as explanatory variables in our model. Given the class of data we use, we analyze the properties of the random error and estimate the model through maximum likelihood, finding significant results from an applied point of view.     

Foster carers' experiences of a paired reading literacy intervention with looked‐after children

Previous studies have shown that paired reading, a structured literacy intervention, is a promising method for improving looked‐after children's literacy skills. The aim of this study was to explore variations in foster carers' experiences of conducting the intervention. Interviews were carried out with 15 Swedish foster carers with varying experiences in programme compliance and of practicing the method. Findings suggest that the intervention process starts with getting carers involved, which seems to be dependent on a positive carer attitude. Integrating the reading training in the everyday life is another important aspect, which evolves around motivating the child and prioritizing the reading sessions. Furthermore, the results emphasize the need of having a flexible approach when delivering the intervention. The results suggest that it is possible to engage foster carers in literacy training for looked‐after children and that paired reading can provide a model for competent reading and also result in improved child/carer relations. However, participants need support, and in some cases adjustments in the day‐to‐day delivery of the intervention are required.     

Nonparametric estimation in semi-parametric univariate mixture models

We introduce new estimates of the mixing proportions, locations, and variances of the components of a finite univariate mixture model. We assume that the components are symmetric and differ only in the locations. No parametric model assumptions are imposed on the components. Further, when there is additional information available in the form of training samples that contain information concerning the mixing proportion, the new methods are robust to the symmetry assumption.     

On screening samples in the laboratory and factors in factorial investigations

Procedures such as group testing and fractional replication can greatly reduce the workload. The former is especially efficient when the presence of a characteristic in samples is low. Fractional replication can greatly reduce the amount of experimentation when some of the parameters associated with a factorial are nonexistent or negligible. Supersaturated fractional replication can be used to efficiently screen factors when it is suspected that they may not affect a process but it is desired to check this suspicion. There are many types of grouping and pooling material in an investigation. Some of these are discussed as are the interrelationships among the above procedures.     

Almost unbiased ratio and product estimators based on interpenetrating subsamples

This paper proposes two classes of almost unbiased ratio and product estimators, in the case of interpenetrating subsample designs, which include the estimators considered by earlier authors. Several other almost unbiased ratio and product estimatbrs are given whlch are particular members of the proposed classes of estimators. Optimum estimators are also identified in these classes.     

Estimates of the parameters of type-II extreme value distribution from censored samples

Maximum likelihood estimators of a Type-II extreme value distribution are derived from doubly censored samples. The asymptotic variances and covariances of the maximum likelihood estimators are discussed and these are numerically evaluated for different censoring proportions q₁ = 0.0(0. l) (0.9) from below and q₂ = 0.0 (0. l) (0.9- q₁) from above. The asymptotic relative efficiencies of the parameter estimates revealed that lower order statistics are more important for estimating the parameters of Type-II extreme value distribution as compared to higher order statistics.     

Maximum Likelihood Estimation of a Poisson Parameter in a Model of Equioverlapping Samples:A Simulation Study

In a model of equioverlapping samples maximum likelihood estimation of a Poisson parameter is examined and compared with two linear unbiased estimations by mean squared error. Since a likelihood estimator is not explicitly available in general, a simulation study has been performed and the results are illustrated