A heuristic to minimize total flow time in permutation flow shop

In this paper, we address an n-job, m-machine permutation flow shop scheduling problem for the objective of minimizing the total flow time. We propose a modification of the best-known method of Framinan and Leisten [An efficient constructive heuristic for flowtime minimization in permutation flow shops. Omega 2003;31:311–7] for this problem. We show, through computational experimentation, that this modification significantly improves its performance while not affecting its time-complexity.     

Some subset selection problems

Consider that we have a collection of k populations π₁, π₂…,π_k. The quality of the ith population is characterized by a real parameter θ_i and the population is to be designated as superior or inferior depending on how much the θ_i differs from θ_max = max{θ₁, θ₂,…,θ_k}. From the set {π₁, π₂,…,π_k}, we wish to select the subset of superior populations. In this paper we devise rules of selection which have the property that their selected set excludes all the inferior populations with probability at least 1?α, where a is a specified number.     

Testing for superadditivity of the mean value function of a non-homogeneous poisson process

Consider a non-homogeneous Poisson process, N(t), with mean value function Λ(t) and intensity function λ(t). A conditional test of the hypothesis that the process is homogeneous, versus alternatives for which Λ(t) is superadditive, was proposed by Hollander and Proschan (1974). A new test for superadditivity of Λ(t), which is based on a linear combination of the occurrence times of the process N{t) is suggested in this paper. Though this test has the same Pitman efficiency as the Hollander-Proschan test, it is shown by Monte-Carlo simulation that our test has more power for many important alternatives. Tables for the exact null distribution of the test statistic have been given.     

Generalized Supremum Tests for the Equality of Cause Specific Hazard Rates

In this paper we propose two new classes of asymptotically distribution-free Renyi-type tests for testing the equality of two risks in a competing risk model with possible censoring. This work extends the work of Aly, Kochar and McKeague [1994, Journal of American Statistical Association, 89, 994–999] and many of the existing tests for this problem belong to these newly proposed classes. The asymptotic properties of the proposed tests are investigated. Simulation studies are done to compare the performance with existing tests. A competing risks data set is analyzed to demonstrate the usefulness of the procedure.     

PERCEPTION AND PREFERENCE CONGRUENCY: A COLOR REPLICATION*

The work of Doehlert has involved an investigation of automobile-color preferences and their relationship to color perceptions. For the most part, Doehlert's work has pointed to congruency. Other work, dealing with formal congruency testing between unfolded preferences and perceptions, has proven somewhat disappointing. Since the nature of the stimulus set may play a role in a resulting congruency, this study will attempt to replicate and extend the work of Doehlert. Given replication, a framework for stimulus set uniqueness may be obtained. Either way, keynote implications for marketing decision making are to be developed.     

Policy Simulation of the Indian Silk Industry through an Econometric Model

This study aimed at understanding and quantifying the relationship between the important variables of the various subsectors of the Indian silk industry through an econometric simulation model, and using the model for forecasting as well as policy simulations. Forecasts of the endogenous variables of the system (demand, supply, and prices of mulberry cocoons, raw silk, and silk fabric) for the period 1991–92 to 2000–01 indicates that the growth in the industry will slow down in the future. Policy simulations were undertaken to assess the changes in the import price of raw silk, export price of fabrics, and regulation of the quantity of imports of raw silk on the silk industry. While imports and exports were closely linked, their impact on the silk industry was not very high. It was also revealed that the income of the consumers and mulberry acreage have significant influence on the industry.     

Estimation of variance components in staggered nested designs

SUMMARY Variance components are estimated by two different methods for a general p stage random-effects staggered nested design. In addition to estimation from an analysis of variance, a new approach is introduced. The main features of this new technique are its simplicity and its ability to yield non-negative estimates of the variance components. The performances of the two procedures are compared using simulation and the meansquared-error criterion.     

Classification with multiple independent measurements under a separate sampling scheme

In this article, we consider the problem of classifying m independent repeated (multiple) observations coming from the same population under a separate sampling scheme. We derive the asymptotic risk of the proposed NN type classification rule and obtain the upper and lower bounds for it in specific cases in terms of Bayes risk. Using a Monte Carlo simulation study we show that, as m increases, the classification risk decreases.