摘要:

A large clinical comparison of pain killers used in the treatment of arthritis was conducted using a sequential design. The trial presented two major challenges: there were three treatments to be compared, and patients were assessed annually for up to 7 years. Treatment comparisons were made by selecting appropriate pairwise comparisons, to which standard theory could be applied. Rules concerning actions to take in the event of each stopping criterion being reached were evaluated by simulation. The annual assessments were used to create an interval-censored survival time: the year during which “disease progression” first occurred.

ISSN:1054-3406    

DOI:10.1080/10543409708835192

出版商:Marcel Dekker, Inc.    

年代:1997

数据来源: Taylor

摘要:

Multiple comparisons are commonly seen in clinical trials and many other fields. An example, which is the focus of this paper, is the comparison of several test treatments (possibly different doses of a compound) with placebo (control). It is well known that steps must be taken to control the type I error rate when multiple testing is performed. We introduce the concept of the strong stagewise family error rate and propose a multiple comparison procedure to control this error rate. The proposed procedure is compared to Dunnett's step-down procedure when there are two test treatment groups and a placebo group.

ISSN:1054-3406    

DOI:10.1080/10543409708835193

出版商:Marcel Dekker, Inc.    

年代:1997

数据来源: Taylor

摘要:

This paper deals with a method of analyzing incomplete data, forming a monotone pattern, from a within-subject design with baseline measurements. An assumption of multivariate normality with antedependence structure is made for both the baseline measurements and the response measurements. Adjusted means for the period-by-sequence cells and their dispersion matrix are obtained. Large sample tests are proposed for testing various hypotheses. A numerical example is given to illustrate the methodology.

ISSN:1054-3406    

DOI:10.1080/10543409708835194

出版商:Marcel Dekker, Inc.    

年代:1997

数据来源: Taylor

摘要:

The implications of drop-outs for power of random regression model (RRM) tests of significance for differences in the rate of change produced by two treatments in a randomized parallel-groups design were investigated by Monte Carlo simulation methods. The two-stage RRM fitted a least squares linear regression equation to all of the available data for each individual, and then ANOVA or ANCOVA tests of significance were applied to the resulting slope coefficients. The tests of significance were adequately protected against type I error, but power was seriously eroded by the presence of drop-outs. Simple endpoint analyses with baseline and time-in-treatment covaried proved more robust against the power degradations.

ISSN:1054-3406    

DOI:10.1080/10543409708835195

出版商:Marcel Dekker, Inc.    

年代:1997

数据来源: Taylor

摘要:

This paper presents the advantages of rank analysis of covariance in contrast to the Mantel-Haenszel procedure in the presence of a covariate. In this paper, data from a clinical trial with an indication for seborrheic dermatitis, which afflicts multiple anatomical regions, is presented. This paper presents analysis performed using both the Mantel-Haenszel procedure and rank analysis of covariance for separate anatomical regions, as well as for the combined anatomical regions. The analysis for the combined anatomical regions involves weighted sums over different strata.

ISSN:1054-3406    

DOI:10.1080/10543409708835196

出版商:Marcel Dekker, Inc.    

年代:1997

数据来源: Taylor

摘要:

Reference ranges are used in preclinical drug safety studies to screen experimental data for atypical values. The methods used most often to construct sample reference ranges are essentially large sample methods and may flag too few “atypical” values. It is better to generate finite sample reference ranges by modifying existing methods used for constructing tolerance intervals. We define validity and efficiency for reference ranges and discuss the validity and efficiency of the methods described. A finite sample distribution-free method emerges as the clear winner.

ISSN:1054-3406    

DOI:10.1080/10543409708835197

出版商:Marcel Dekker, Inc.    

年代:1997

数据来源: Taylor

摘要:

In dissolution testing multiple dissolution measurements at specific time points are needed in quality control when the compliance of the product requires controlled dissolution throughout the time course. The dissolution specification based on general multivariate confidence region was proposed by Chen and Tsong (8). This paper presents two alternative procedures when the dissolution profile consists of important measurements at more than 4 time points. In the first procedure, when the dissolution profile can be described by a physical curve through modeling, the dissolution specification is developed based on the confidence region of the parameters of the physical curve. In the second procedure, the principal components (PCS) as the linear combinations of the dissolution measurements are identified and dissolution specification is set based by the confidence intervals of the values of principal components. In both approaches the specification can be set at lower dimensions than the general multivariate confidence region approach. A single-stage acceptance rule can be used in both approaches by first projecting the dissolution values of each tablet in the new testing batch onto the determined parameters axes (through modeling in modeling approach and through projection on the selected PCS in principal component approach). Then check if the projections of the new tablet fall within the specifications. Finally, count the number of tablets that fall outside the specification limits and reject the batch if the proportion of out-of-specification tablet is high and accept the lot for release if the proportion is low.

ISSN:1054-3406    

DOI:10.1080/10543409708835198

出版商:Marcel Dekker, Inc.    

年代:1997

数据来源: Taylor

摘要:

We present an approximate method to compare the difference of the means of two groups of populations by indirect unpaired data. This indirect data structure occurs in receptor autoradiography, where the tissue distribution of receptors is visualized in the form of ligand bindings. This visualization is indirect because we can only observe and measure nonspecific bindings in one autoradiograph and total bindings in another autoradiograph. The distribution of receptors is obtained by subtracting the nonspecific bindings from the total bindings. Besides the reasoning of our method, an example is given using our experimental data.

ISSN:1054-3406    

DOI:10.1080/10543409708835199

出版商:Marcel Dekker, Inc.    

年代:1997

数据来源: Taylor

摘要:

Electrospray ionization (ES) is a novel method used in mass spectrometry (MS) for producing gas-phase ions from substances in solutions. Common practices for molecular mass estimation from ES spectra summarize the spectrum as a single peak giving no estimate of uncertainty or treat each peak as an independent molecular mass measurement. ES-MS data analysis showed that each peak in an ES spectrum does not always provide an independent measure of molecular mass. Underestimation of measurement uncertainty is a possible result. An elementary time series method, the Yule-Walker equations, was applied to molecular mass estimation from ES data.

ISSN:1054-3406    

DOI:10.1080/10543409708835200

出版商:Marcel Dekker, Inc.    

年代:1997

数据来源: Taylor

ISSN:1054-3406    

DOI:10.1080/10543409708835201

出版商:Marcel Dekker, Inc.    

年代:1997

数据来源: Taylor