A New Framework for Manufacturing Planning and Control Systems*

This paper presents a new framework for manufacturing planning and control systems which we call iterative manufacturing planning in continuous time (IMPICT) that appears to have several advantages over the well-known material requirements planning (MRP) framework. IMPICT explicitly considers capacity constraints and total system cost (including tardiness) to determine order sizes, order release/due dates, and operation schedules in a deterministic, multi-level, finite horizon, dynamic demand environment. Continuous time scheduling variables allow setups to be carried over from one period to the next. Three new heuristics built on the IMPICT framework are presented and tested in a simulation-based, full-factorial experiment with a wide variety of problem environments. The benchmark for the experiment was materials requirements planning with operations sequencing (MRP/OS) implemented with best-case, fixed planned lead times. The experiment showed that all three heuristics were statistically better than MRP/OS. The total cost for the order merging (OM) heuristic was 25 percent better than the total cost for MRP/OS. Computational times for OM were substantially larger than for MRP/OS; however, the computational times in the experiment suggest that OM is still computationally viable for large-scale batch manufacturing environments found in industry. IMPICT is superior to standard MRP systems because it explicitly considers capacity constraints and total system costs when it creates a materials plan. IMPICT is superior to linear programming-based approaches to finite loading and scheduling found in the literature because it allows setups to be carried over from one period to another and because it is computationally viable for realistic-sized problems.     

How does information sharing affect first-tier suppliers’ flexibility? Evidence from the automotive industry in Sweden

This study addresses the critical research issue of how supplier delivery performance can be enhanced by integrating information sharing into volume and delivery flexibility. This study developed a research model to relate information sharing on demand forecasts and inventory data between original equipment manufacturers (OEMs) and first-tier suppliers. Based on a sample of 52 suppliers from automotive industry in Sweden, partial least squares structural equations modelling (PLS-SEM) was used to assess the model. The results confirm that sharing demand forecasts is a key enabler of supplier volume and delivery flexibility while sharing inventory data is not. The study contributes to enlarging the knowledge about supply chain management from the suppliers’ perspective. It also contributes to knowledge by validating the conceptual model and operationalisation of constructs. The study also has practical contribution in which management should focus on improving communication and collaboration practices with OEMs for effective sharing of demand forecasts.     

Moving Towards Happiness?

We add to the literature on the driving forces of international migration. While the existing literature establishes that income differences, migration costs and certain other factors (e.g. climate or human rights) affect the migration decision, we focus on the broader role of non‐pecuniary factors. We include well‐being measures in a standard model of bilateral migration flows and enrich the analysis further by testing the effects on migration of inequality in happiness within a country. Our findings that both the mean and standard deviation of happiness – in both origin and destination countries – help explain bilateral migration flows over and above any income effect, indicates the need to incorporate both pecuniary and non‐pecuniary factors when modelling migration choices.     

The Persistence of Racial Disadvantage: The Socioeconomic Attainments of Single-Race and Multi-Race Native Americans

Using data from the 2000 U.S. Census, we investigate the schooling and earnings of single-race and multi-race Native Americans. Our analysis distinguishes between Single-Race Native Americans, biracial White Native Americans, biracial Hispanic-White Native Americans, and biracial Black Native Americans. Further differentiating by gender, the results indicate significant variation in socioeconomic attainments across these different Native American groups although almost all of them are in some way disadvantaged relative to non-Hispanic, non-Native American whites. The most disadvantaged group tends to be Single-Race Native Americans who have the lowest levels of schooling as well as lower earnings relative to non-Hispanic, non-Native American whites who are comparable in terms of schooling, age, and other basic demographic characteristics. The results demonstrate notable differentials by the racial/ethnic type of Native American group as well as by gender. In the case of men, all of the Native American groups have clear socioeconomic disadvantages. One contrast is that migration slightly increases the earnings of men but it slightly decreases the earnings of women. We interpret these findings as underscoring how measured socioeconomic differentials between demographic groups are significantly affected by the categorization of race/ethnicity in surveys and by how persons choose to be enumerated in terms of those categories.     

General Feelings Toward Unions and Employers as Predictors of Union Voting Intent

The union voting intention literature shows that many nonunion employees who indicate that they think unions are instrumental in increasing wages, benefits, and working conditions would vote against forming a union. Although American workers have often been characterized as pragmatic with regard to their support for unions, the “disconnect” between union beliefs and union voting intentions just described suggests that more subtle forces are at work. In this paper, it is shown empirically that union instrumentality is a limited predictor of union voting intentions for a recent national cross-section of workers. Rather, more general feelings toward unions and employers are primary. These accounted for a large portion of the variance in union voting intentions, with general feelings towards unions by far the most critical predictor. A concluding section discusses whether the results may reflect changes in union power and changes in employee views of unions. Areas for future research are discussed.     

Psychometric Properties of the Family Inventory of Resources and Stressors in Families of Children with Emotional/Behavior Disorders: Ethnic/Racial and Developmental Differences

The Family Inventory of Resources and Stressors (FIRST) has been shown to have adequate psychometric properties in the assessment of families of children with emotional and behavior disorders (EBD). However, the extent to which ethnic/racial and developmental differences moderate the psychometric properties of this instrument is unknown. The study sample consisted of 150 families with an EBD child consecutively admitted to the Astor Transitions Program. This study seeks (1) to conduct a psychometric analysis of the FIRST subscales among African American and Hispanic/Latino families with older students versus early childhood students with EBD, and (2) to determine whether profiles will show greater stress for families of older students due to longer exposure to their EBD. Alpha coefficients were computed with a cutoff of 0.70 (or higher) indicating acceptable internal consistency reliability. Criterion variables reflecting family environment, mental health, and level of service correlated with relevant FIRST subscales assessed validity. Ethnic/racial and developmental effects were found to moderate the psychometric properties of the FIRST. No statistically significant between-group mean differences on the FIRST were found for families of early childhood versus older EBD students. Despite evidence of response bias on the part of families and lack of standardization during test administration by caseworkers, the current findings still reveal adequate reliability and limited validity of FIRST subscales.