Joseph Voelkel

Joseph Voelkel
Rochester Institute of Technology | RIT · School of Mathematical Sciences

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37
Publications
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1,392
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Publications

Publications (37)
Article
We introduce order-of-addition (OofA) experiments, which study the order in which m components are applied, such as the order in which m chemicals are added to a mix or m layers to a film. We discuss a way for designing such experiments using the traditional paradigm of factors. A full design with m components requires m! runs, but we show that opt...
Article
I introduce systematic methods to create optimal designs for order-of-addition (OofA) experiments, those that study the order in which m components are applied—for example, the order in which chemicals are added to a reaction or layers are added to a film. Full designs require m! runs, so I investigate design fractions. Balance criteria for creatin...
Preprint
Full-text available
We analyze extensions of the Poisson process in which any interarrival time that exceeds a fixed value $r$ is counted as an interarrival of duration $r$. In the engineering application that initiated this work, one part is tested at a time, and $N(t)$ is the number of parts that, by time $t$, have either failed, or if they have reached age $r$ whil...
Article
In this case study, we examine the reliability of a device whose material was produced over several heats, where the quality metric of the material is the content of a certain element in the material. The analyses revealed a number of issues, including rounded data values as well as periodicity and tilting in the two dimensions of the production pr...
Article
Full-text available
We introduce designs for order-of-addition (OofA) experiments, those that study the order in which m components are applied. Full designs require m! runs, so we investigate design fractions. Balance criteria for creating such designs employ an extension of orthogonal arrays (OA's) to OofA-OA's. A connection is made between D-efficient and OofA-OA d...
Article
Full-text available
Article
The treatment-design portion of fractionated two-level split-plot designs is associated with a subset of the 2n–k fractional factorial designs. The concept of aberration is then extended to these splitplot designs to compare designs. Two methods are presented for constructing two-level minimumaberration split-plot designs, along with examples. An e...
Article
Full-text available
Typically a regression approach is applied in order to identify the constituents present in a hyperspectral image, and the task of species identification amounts to choosing the best regression model. Common model selection approaches (stepwise and criterion based methods) have well known multiple comparisons problems, and they do not allow the use...
Chapter
If only a fraction of all the treatment combinations of a full factorial design are selected to be run, the resulting design is called a fractional factorial design. By carefully deciding which fraction of the treatment combinations to run, it is possible to construct fractional factorial designs with good properties. We examine these designs in de...
Article
We consider gauge repeatability and reproducibility (R&R) analyses for two-dimensional data when the engineering tolerance associated with measurements is a circle. We develop summaries for repeatability, reproducibility, and R&R, by employing the diameters of circles that provide 99% capture rates. We derive an inequality between a one-dimensional...
Article
The concept of 3.4 parts per million (ppm) used in measuring quality characteristics is discussed. It is assumed that the quality characteristic being measured has a normal distribution with mean μ and standard deviation σ. The actual value of 3.4 ppm refers to the fraction that would fall either above μ+4.5σ or below μ-4.5σ. It is found that it ta...
Article
Full-text available
A frequently stated advantage of fractional-factorial (FF) designs over one-factor-at-a-time (1FAT) designs is their high relative efficiency. We study k-factor, 2k-run designs, where k is a power of 2 or is divisible by 4, for which the usually stated relative efficiency is k in favor of the resolution IV FF design over an orthogonal 1FAT design....
Article
Full-text available
There is only a weak and poorly defensible statistical link between the notion of a so-called 6σ process and the 3.4 parts per million defect rate that is usually associated with it in the Six-Sigma literature. In this note, we comment on the purported link and illustrate two reasonable ways in which a process may be related to a defect rate. First...
Article
We consider gauge repeatability and reproducibility (R&R) analyses for two-dimensional date when the engineering tolerance associated with measurements is a circle. We develop summaries for repeatability, reproducibility, and R&R by employing the diameters of circles that provide 99% capture rates. We derive an inequality between the results of a o...
Article
We examine three test statistics that appear suited to analyzing supersaturated designs. All three statistics are shown to have undesirable, somewhat surprising, asymptotic power properties. Suggestions are given for improved analysis methods.
Article
Full-text available
Abstract In some experiments, the response is binary and one factor is being studied to estimate the factor setting at which probability of failure is a specified value, such as 0.10. In addition, data for such experiments are sometimes naturally collected one run at a time. The difficulty in such experiments, compared to experiments in which the r...
Article
In cancer clinical trials, tumor response, defined in terms of predetermined relative decrease in tumor size, and overall survival are often used to evaluate treatment efficacy. Investigators often attempt to demonstrate a positive relationship betwen the two measures by comparing the survival of the responders to that of the non-responders. The bi...
Article
A common practice in the analysis of clinical trials is the assumption of proportional hazards given the covariates. When this assumption is appropriate but an important covariate is omitted, the ratio of the hazards is shown to be less than the constant proportion (assumed to be greater than 1). In certain cases it can even be less than 1. Limitin...
Article
A class of semi-Markov models, those which have proportional hazards and which are forward-going (if state $j$ can be reached from $i$, then $i$ cannot be reached from $j$), are shown to fit into the multiplicative intensity model of counting processes after suitable random time changes. Standard large-sample results for counting processes followin...
Article
Production of monodispersed cell suspensions from primary human breast tumors is difficult due to the predominant stromal composition of most breast tumors. Our studies were designed to optimize dispersion of breast tumors of known stromal content and histopathology. In a first series of experiments three enzymatic protocols were compared to disper...
Article
Full-text available
The relative antiproliferative activity of natural interferons alpha and beta was compared in 43 in vitro assays of 25 human cell lines or strains. After 120 hr of continuous exposure to 100 units/ml, interferon beta produced greater than 20% growth inhibition in 22 cells (88%), and interferon alpha produced 20% growth inhibition in 9 cells (36%)....
Article
The therapeutic effectiveness of combining tamoxifen with a combination chemotherapy regimen was tested in 135 patients with advanced breast cancer previously treated with chemotherapy. Patients were randomly allocated to received dibromodulcitol + Adriamycin (DA, 55 patients) or DA + tamoxifen (DAT, 67 patients). An additional 13 patients less tha...
Article
Fifty-nine evaluable patients with stage III bronchogenic carcinoma, participating in a randomized clinical trial evaluating the effect of adjuvant immunotherapy with levamisole or BCG in the treatment of clinically advanced lung cancer, were studied for their immunocompetence by in vitro and in vivo assays. Immunological tests consisted of measure...
Article
Typescript. Thesis (Ph. D.)--University of Wisconsin--Madison, 1980. Vita. Includes bibliographical references (leaves 125-127).

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