scholarly journals A two-stage procedure on comparing several experimental treatments and a control—the common and unknown variance case

2005 ◽  
Vol 2005 (1) ◽  
pp. 47-58
Author(s):  
John Zhang ◽  
Pinyuen Chen ◽  
Yue Fang
Keyword(s):  
Selection Rule ◽  
Selection Procedure ◽  
Experimental Treatment ◽  
Correct Decision ◽  
Two Stage ◽  
Sample Mean ◽  
Indifference Zone ◽  
Unknown Variance ◽  
Preference Zone ◽  
Experimental Treatments

This paper introduces a two-stage selection rule to compare several experimental treatments with a control when the variances are common and unknown. The selection rule integrates the indifference zone approach and the subset selection approach in multiple-decision theory. Two mutually exclusive subsets of the parameter space are defined, one is called the preference zone (PZ) and the other, the indifference zone (IZ). The best experimental treatment is defined to be the experimental treatment with the largest population mean. The selection procedure opts to select only the experimental treatment which corresponds to the largest sample mean when the parameters are in the PZ, and selects a subset of the experimental treatments and the control when the parameters fall in the IZ. The concept of a correct decision is defined differently in these two zones. A correct decision in the preference zone (CD1) is defined to be the event that the best experimental treatment is selected. In the indifference zone, a selection is called correct (CD2) if the selected subset contains the best experimental treatment. Theoretical results on the lower bounds for P(CD1) in PZ and P(CD2) in IZ are developed. A table is computed for the implementation of the selection procedure.

scholarly journals An integrated selection formulation for the best normal mean: the unequal and unknown variance case

2002 ◽  
Vol 6 (1) ◽  
pp. 23-42 ◽  
Author(s):  
Pinyuen Chen ◽  
Jun-Lue Zhang
Keyword(s):  
Sample Size ◽  
Parameter Space ◽  
Correct Selection ◽  
Indifference Zone ◽  
Unknown Variance ◽  
Normal Mean ◽  
Favorable Configuration ◽  
Preference Zone ◽  
Selected Subset ◽  
Least Favorable Configuration

This paper considers an integrated formulation in selecting the best normal mean in the case of unequal and unknown variances. The formulation separates the parameter space into two disjoint parts, the preference zone (PZ) and the indifference zone (IZ). In the PZ we insist on selecting the best for a correct selection (CS1) but in the IZ we define any selected subset to be correct (CS2) if it contains the best population. We find the least favorable configuration (LFC) and the worst configuration (WC) respectively in PZ and IZ. We derive formulas for P(CS1|LFC), P(CS2|WC) and the bounds for the expected sample size E(N). We also give tables for the procedure parameters to implement the proposed procedure. An example is given to illustrate how to apply the procedure and how to use the table.

The Duty to Rescue and Randomized Controlled Trials Involving Serious Diseases

2018 ◽  
Vol 15 (3) ◽  
pp. 298-323
Author(s):  
Joseph Millum ◽  
David Wendler
Keyword(s):  
Medical Research ◽  
Randomized Controlled Trials ◽  
Experimental Treatment ◽  
Controlled Trials ◽  
Potential Treatment ◽  
Randomized Controlled ◽  
Experimental Treatments ◽  
Effective Treatments

During the recent Ebola epidemic, some commentators and stakeholders argued that it would be unethical to carry out a study that withheld a potential treatment from affected individuals with such a serious, untreatable disease. As a result, the initial trials of experimental treatments did not have control arms, despite important scientific reasons for their inclusion. In this paper, we consider whether the duty to rescue entails that it would be unethical to withhold an experimental treatment from patient-participants with serious diseases for which there are no effective treatments, even when doing so is scientifically necessary to test the effectiveness of the treatment. We argue that the duty to rescue will rarely apply. The context of medical research also throws new light on the content of the duty to rescue, since the interests of future patients—who stand to benefit from the fruits of medical research—are relevant to whether the duty applies.

A Two-Stage Hybrid Algorithm for Flexible Job-Shop Scheduling

2011 ◽  
Vol 268-270 ◽  
pp. 476-481
Author(s):  
Li Gao ◽  
Ke Lin Xu ◽  
Wei Zhu ◽  
Na Na Yang
Keyword(s):  
Genetic Algorithm ◽  
Hybrid Algorithm ◽  
Job Shop ◽  
Flow Shop ◽  
Job Shop Scheduling ◽  
Selection Procedure ◽  
Dynamic Programming Method ◽  
Two Stage ◽  
Simulated Annealing Genetic Algorithm ◽  
Mutation Operators

A mathematical model was constructed with two objectives. A two-stage hybrid algorithm was developed for solving this problem. At first, the man-hour optimization based on genetic algorithm and dynamic programming method, the model decomposes the flow shop into two layers: sub-layer and patrilineal layer. On the basis of the man-hour optimization，A simulated annealing genetic algorithm was proposed to optimize the sequence of operations. A new selection procedure was proposed and hybrid crossover operators and mutation operators were adopted. A benchmark problem solving result indicates that the proposed algorithm is effective.

Robustness of a Two-Stage Selection Procedure When Variances Are Unequal

2015 ◽  
Vol 34 (3) ◽  
pp. 336-349
Author(s):  
Yoshikazu Takada ◽  
Naoki Shiotome
Keyword(s):  
Selection Procedure ◽  
Two Stage

A Two-Stage Design for Choosing among Several Experimental Treatments and a Control in Clinical Trials

Biometrics ◽  
1989 ◽  
Vol 45 (2) ◽  
pp. 537 ◽  
Author(s):  
Peter F. Thall ◽  
Richard Simon ◽  
Susan S. Ellenberg
Keyword(s):  
Clinical Trials ◽  
Two Stage ◽  
Stage Design ◽  
Two Stage Design ◽  
Experimental Treatments

A Note on the Length and Passing Score of a Mastery Test

1976 ◽  
Vol 1 (4) ◽  
pp. 359-364 ◽  
Author(s):  
Rand R. Wilcox
Keyword(s):  
Selection Procedure ◽  
Ranking And Selection ◽  
Test Length ◽  
Indifference Zone ◽  
Search Routine ◽  
Passing Score

Using an indifference zone formulation, Fhanér has described a ranking and selection procedure for determining the appropriate length of a mastery test. The purpose of this note is to relate Fhanér’s solution to one given by Millman, to give a criterion for the choice of a passing score, and to describe a search routine which will always yield the appropriate test length and implied passing score.

scholarly journals Combined effects of elevated epilimnetic temperature and metalimnetic hypoxia on the predation rate of planktivorous fish

2019 ◽  
Vol 41 (5) ◽  
pp. 709-722 ◽  
Author(s):  
Piotr Maszczyk ◽  
Ewa Babkiewicz ◽  
Krzysztof Ciszewski ◽  
Kamil Dabrowski ◽  
Przemysław Dynak ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Experimental Treatment ◽  
Fish Predation ◽  
Predation Rate ◽  
Control Treatment ◽  
Combined Effects ◽  
Daphnia Longispina ◽  
Scardinius Erythrophthalmus ◽  
Tank System ◽  
Experimental Treatments

Abstract Increased temperature in the epilimnion and hypoxia in the metalimnion of a lake would result in an increase of positive-size-selective fish predation on zooplankton and in turn in a decrease of mean body size in zooplankton populations and communities. We tested this hypothesis in four types of experiments with juvenile rudd (Scardinius erythrophthalmus) foraging on Daphnia longispina in an indoor twin column tank system. In each experiment of the first three types, one column contained one of three types of experimental treatments differing from the control treatment (in the other column) by the following: (i) elevated temperature in the epilimnion, (ii) hypoxia in the metalimnion and (iii) simultaneous elevated temperature in the epilimnion and hypoxia in the metalimnion. In the fourth type of experiment, the gradients of temperature and oxygen concentration in both columns were the same, but prior to the experiments, Daphnia and fish in the control treatment were acclimated to normoxia and, in the experimental treatment, to hypoxia. The results confirmed our hypothesis, since the predation rate of fish was greater in each of the first three experimental treatments than in the control. We did not detect an effect of the acclimation to hypoxia on the predation rate of the fish.

Adaptive timing of detachment in a tick parasitizing hole-nesting birds

Parasitology ◽  
2011 ◽  
Vol 139 (2) ◽  
pp. 264-270 ◽  
Author(s):  
J. WHITE ◽  
D. J. A. HEYLEN ◽  
E. MATTHYSEN
Keyword(s):  
Experimental Treatment ◽  
Control Treatment ◽  
Control Group ◽  
Suitable Habitat ◽  
Nest Boxes ◽  
Tree Holes ◽  
Ixodes Arboricola ◽  
Experimental Treatments ◽  
Experimental Group ◽  
Engorgement Weight

SUMMARYIn non-permanent parasites with low intrinsic mobility such as ticks, dispersal is highly dependent on host movements as well as the timing of separation from the hosts. Optimal detachment behaviour is all the more crucial in nidicolous ticks as the risk of detaching in non-suitable habitat is high. In this study, we experimentally investigated the detachment behaviour of Ixodes arboricola, a nidicolous tick that primarily infests birds roosting in tree-holes. We infested great tits with I. arboricola larvae or nymphs, and submitted the birds to 2 experimental treatments, a control treatment in which birds had normal access to nest boxes and an experimental treatment, in which the birds were prevented access to their nest boxes for varying lengths of time. In the control group, most ticks detached within 5 days, whereas in the experimental group, ticks remained on the bird for as long as the bird was prevented access (up to 14 days). This prolonged attachment caused a decrease in survival and engorgement weight in nymphs, but not in larvae. The capacity of I. arboricola larvae to extend the duration of attachment in non-suitable environments with no apparent costs, may be an adaptation to unpredictable use of cavities by roosting hosts during winter, and at the same time may facilitate dispersal of the larval instars.

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