Solving a process engineer's manpower-planning problem using analytic hierarchy process

The role of a process engineer (PE) is vital in a high-technology organization. Generic manpower-planning approaches, such as regression or mathematical programming methods, are difficult to apply to PE manpower-planning problem. A simple production-volume to staffing-level ratio did not properly reflect the required PE staffing needs. This research considered both production volume and complexity to plan the required PE staffing level. Production complexity is an indicator of the amount of PE attendance time, and this is innovatively evaluated in the present study using the analytic hierarchy process (AHP). A case study is used to illustrate the proposed methodology.     

Logistic regression analysis of randomized response data with missing covariates

Randomized response is an interview technique designed to eliminate response bias when sensitive questions are asked. In this paper, we present a logistic regression model on randomized response data when the covariates on some subjects are missing at random. In particular, we propose Horvitz and Thompson (1952)-type weighted estimators by using different estimates of the selection probabilities. We present large sample theory for the proposed estimators and show that they are more efficient than the estimator using the true selection probabilities. Simulation results support theoretical analysis. We also illustrate the approach using data from a survey of cable TV.     

Personal and Family Correlates of Resilience Among Adolescents Living in Single-Parent Households in Taiwan

ABSTRACT

Based on the responses of 291 Taiwanese adolescents living with single parents, this article examines the personal (gender and academic performance) and family (gender of parent living together and family type) correlates of resilience of the participants with reference to different psychosocial domains. Whereas girls displayed higher resilience in some dimensions of personal and school resilience domains than did boys, boys experienced higher family resilience than did girls. Better academic performance was positively related to effective coping, personal independence, global personal resilience, and parental expectation on academic performance. Adolescents living with single mothers displayed higher personal independence and family resilience than did adolescents living with single fathers. Compared with adolescents not living with any parent or those who lived with both parents after divorce, adolescents living in nuclear and stem families displayed higher positive orientation to older people and experienced higher family resilience.     

A note on “The EPQ with partial backordering and phase-dependent backordering rate”

Pentico et al. [The EPQ with partial backordering and phase-dependent backordering rate. Omega 2011;39(5):574-7] recently proposed an EPQ model with partial backordering. They tried to determine the minimum average total cost per year from the three cases: to lose all sales, to meet all demand, and to allow stockouts with partial backordering. In this paper, we solve the same model without differential calculus and present a different decision procedure. Without the comparison of those costs, a numerical example is illustrated to determine the optimal production policy by our criteria.     

Age and relative importance of major life domains

Based on a quality of life conceptual model which incorporates the domain comparison process postulated by the self-system perspective, this study empirically examined the relationship between age and domain comparison among adults age 50 and above. Study participants were interviewed through telephone. Domain comparison was measured by asking the participants to rank eight major life domains, based on their importance. Data were analyzed using exploded logit regression models. Among the eight domains studied, the most important was health, followed by family life, religion, friendships, financial situation, spare time, neighborhood, and work. The results indicate that age is significantly associated with domain comparison, which provides preliminary support for the domain comparison process postulated by the self-system perspective.     

Chinese Tally Mark

A tally mark using the Chinese character cheng is another way of counting frequencies.     

Demand switching criteria for multiple products: An inventory cost analysis

In this paper, we consider the problem of demand switching and show how a firm can take advantage of the risk-pooling effect to gain more profit. We examine the case of three products under various switching criteria; a model based on the heuristic approach is developed to determine the switching paths and the corresponding switching rates that yield the optimal profit. A constrained model with limited amount of the switched demand is also developed. In general, the profit increases as a result of higher profit margin or smaller demand variation and correlation. Our result indicates that the profit does not necessarily increase as the switching rate increases; in some cases the profit may even decrease as a result of demand switching. Numerical examples are also included to illustrate the derived models. The developed analytical approach may help practitioners to gain more insight in demand switching and facilitate inventory related decision-making process as well.     

Should We Give Up Domain Importance Weighting in QoL Measures?

The purpose of this article is to examine the recent claims calling for abolishing domain importance weighting in quality of life (QoL) measures by considering the evidence conceptually and empirically. Based on a close review of evidence presented to date, it is suggested that using the range-of-affect hypothesis as a possible explanation of the poor performance of weighted satisfaction composite in predicting or correlating with global satisfaction or QoL measures can be beneficial to our understanding of the life satisfaction literature. However, given the conceptual focus and the empirical approach of the range-of-affect hypothesis presented in the life satisfaction context, using the range-of-affect hypothesis to argue against domain importance weighting raised more questions than answers. Calling for abolishing domain importance weighting in QoL measures, based on the evidence of range-of-affect hypothesis, is premature.     

Validation of A Heteroscedastic Hazards Regression Model

A Cox-type regression model accommodating heteroscedasticity, with a power factor of the baseline cumulative hazard, is investigated for analyzing data with crossing hazards behavior. Since the approach of partial likelihood cannot eliminate the baseline hazard, an overidentified estimating equation (OEE) approach is introduced in the estimation procedure. Its by-product, a model checking statistic, is presented to test for the overall adequacy of the heteroscedastic model. Further, under the heteroscedastic model setting, we propose two statistics to test the proportional hazards assumption. Implementation of this model is illustrated in a data analysis of a cancer clinical trial.     

A comparison of estimators for regression models with change points

We consider two problems concerning locating change points in a linear regression model. One involves jump discontinuities (change-point) in a regression model and the other involves regression lines connected at unknown points. We compare four methods for estimating single or multiple change points in a regression model, when both the error variance and regression coefficients change simultaneously at the unknown point(s): Bayesian, Julious, grid search, and the segmented methods. The proposed methods are evaluated via a simulation study and compared via some standard measures of estimation bias and precision. Finally, the methods are illustrated and compared using three real data sets. The simulation and empirical results overall favor both the segmented and Bayesian methods of estimation, which simultaneously estimate the change point and the other model parameters, though only the Bayesian method is able to handle both continuous and dis-continuous change point problems successfully. If it is known that regression lines are continuous then the segmented method ranked first among methods.