COST INCREASES DUE TO DEMAND UNCERTAINTY IN MRP LOT SIZING

This paper analyzes the cost increases due to demand uncertainty in single-level MRP lot sizing on a rolling horizon. It is shown that forecast errors have a tremendous effect on the cost effectiveness of lot-sizing techniques even when these forecast errors are small. Moreover, the cost differences between different techniques become rather insignificant in the presence of forecast errors. Since most industrial firms face demand uncertainty to some extent, our findings may have important managerial implications. Various simulation experiments give insight into both the nature and the magnitude of the cost increases for different heuristics. Analytical results are developed for the constant-demand case with random noise and forecasting by exponential smoothing. It is also shown how optimal buffers can be obtained by use of a simple model. Although the analysis in this paper is restricted to simplified cases, the results merit further consideration and study. This paper is one of the first to inject forecast errors into MRP lot-sizing research. As such it attempts to deal with one of the major objections against the practical relevance of previous research in this area.     

Widowhood,family size,and post-reproductive Mortality: a comparative Analysis of three populations in Nineteenth-Century Europe

Researchers from a number of disciplines have offered competing theories about the effects oJ childbearing on parents 'postreproductive longevity. The "disposable soma theory" argues that investments in somatic maintenance increase longevity but reduce childbearing. "Maternal depletion" models suggest that the rigors of childrearing increase mortality in later years. Other researchers consider continued childbearing a sign of healthy aging and a predictor of future longevity. Empirical studies have produced inconsistent and contradictory results. Our focus is on the experience of widowhood, which has been ignored in previous studies. We hypothesize that the death of a spouse is a stressful event with long-term consequences for health, especially for women with small children. Data are drawn from historical sources in Sweden, Belgium, and the Netherlands from 1766 to 1980. Postreproductive mortality was highest among young widows with larger families in all three samples. Age at last birth had little or no effect. We conclude that raising children under adverse circumstances can have long-lasting, harmful effects on a mother's health.     

Correcting missing-data bias in historical demography

Studies on population history are often based on incomplete records of life histories. For instance, in studies using data obtained from family reconstitution, the date of death is right censored (by migration) and the censoring time is never observed. Several methods for the correction of mortality estimates are proposed in the literature, most of which first estimate the number of individuals at risk and then use standard techniques to estimate mortality. Other methods are based on statistical models. In this paper all methods are reviewed, and their merits are compared by applying them to simulated and to seventeenth-century data from the English parish of Reigate. An ad hoc method proposed by Ruggles performs reasonably well. Methods based on statistical models, provided they are sufficiently realistic, give comparable accuracy and allow the estimation of several other quantities of interest, such as the distribution of migration times.     

Changing Indigeneity Politics in Indonesia: From Revival to Projects

Through the discourse of indigeneity, rural communities around the world are joining a global network of rural justice seekers. By articulating grievances collectively, they demand state recognition while seeking support from NGOs and international development organisations. In Indonesia, the manifestation of indigenous ‘adat’ politics is no longer confined to the national struggle for the recognition of land rights, but instead, has proliferated into many localised short term ‘adat projects’. This introduction to the TAPJA special issue on adat demonstrates that both the rural poor and local elites can be the initiators or recipients of these adat projects but, at the current juncture, the latter are better positioned to benefit from such projects. The special issue shows that in Indonesia, where adat is often firmly entrenched in the state, the promotion of indigeneity claims can work in contradictory ways. Findings from across the special issue show that adat projects tend to reinforce the power of the state, rather than challenging it.     

Demographic differences in response rates for PHQ9 in a university student population

Objective: To examine differences in complete response rates for depression screening questions based on demographic characteristics. Methods: Cross-sectional study examining associations between demographic characteristics and completely responding depression-screening questions. Participants: “Healthy Minds Study” data, collected in a public University in February 2016, where 7,326 students participated. Results: women (AOR: 0.69; 95% CI =0.57–0.83) and gay/lesbian students (AOR: 0.24; 95% CI =0.10–0.60) had better complete response rates. Non-US (AOR: 1.46; 95% CI =1.03–2.07), black (AOR: 3.32; 95% CI =1.92–5.77), and Middle-Eastern students (AOR: 3.73; 95% CI =1.73–8.02) had lower complete response rates. Conclusions: Our study shows sex, gender, citizenship, and race categories have significant differences in complete response rates for the outcome. Our findings have several implications; including recognizing interventions for depression based on responders may not target those that tend to be “partial-responders”. Efforts in survey design, recruiting and completion of surveys should be maximized.     

Measuring ambiguity preferences: A new ambiguity preference survey module

Journal of Risk and Uncertainty - Ambiguity preferences are important to explain human decision-making in many areas in economics and finance. To measure individual ambiguity preferences, the...     

Cross Validation of the Gambling Problem Severity Subscale of the Canadian Adolescent Gambling Index (CAGI/GPSS) on a Sample of Ontario High School Students

This paper reports on the cross validation of the Gambling Problem Severity Subscale of the Canadian Adolescent Gambling Index (CAGI/GPSS). The CAGI/GPSS was included in a large school based drug use and health survey conducted in 2015. Data from students in grades 9–12 (ages 13–20 years) derived from the (N = 3369 students). The CAGI/GPSS produced an alpha of 0.789. A principle component analysis revealed two eigenvalues greater than one. An oblique rotation revealed these components to represent consequences and over involvement. The CAGI/GPSS indicated that 1% of the students fell into the “red” category indicating a severe problem and an additional 3.3% scored in the “yellow” category indicating low to moderate problems. The CAGI/GPSS was shown to be significantly correlated with gambling frequency (r = 0.36), largest expenditure (r = 0.37), sex (more likely to be male) (r = ?0.19), lower school marks (r = ?0.07), hazardous drinking, (r = 0.16), problem video game play (r = 0.16), as well as substance abuse. The CAGI/GPSS was cross validated using a shorted version of the short SOGS, r = 0.48. In addition the CAGI/GPSS and short SOGS produced very similar patterns of correlations results. The results support the validity and reliability of the CAGI/GPSS as a measure of gambling problems among adolescents.     

Gender and social conformity: Do men and women respond differently to social pressure to vote?

In this paper, we re-analyze data from a large-scale field experiment (N = 344,084) on voter turnout in order to determine whether men and women respond differently to social pressure aimed at voter mobilization. To date, there have been mixed results regarding the interaction between a person’s gender and receptivity to social influence. On the whole, our analyses confirm prior findings that social pressure increases voter turnout but uncover little to no evidence of gender differences in receptivity to social pressure cues in the context of political participation.     

Parental Divorce,Residence Arrangements,and Contact Between Grandchildren and Grandparents

When parents divorce, grandparents can play a supportive role in the lives of their grandchildren, but a parental divorce may also put grandchild–grandparent ties under pressure. In this study the authors investigated how grandchildren of married and divorced parents differ in the frequency of face‐to‐face contacts with grandparents and how this is mediated by postdivorce residence arrangements. Based on the multi‐actor survey “Divorce in Flanders,” they used reports of contact provided by more than 1,000 grandchildren and compared them with more than 1,100 grandparent reports for validation. The results showed that grandchildren from divorced parents have fewer contacts with their grandparents than grandchildren whose parents are married but that it is the postdivorce residence arrangement of grandchildren that produces this result. When grandchildren live with their divorced father or in a shared residence arrangement, they even see paternal grandparents more often than grandchildren with married parents.