Longitudinal Analysis of Employment and Unemployment Based on Matched Rotation Samples

ABSTRACT: The purpose of this paper is to provide methodology to fit longitudinal data on employment and unemployment generated by the rotation sampling schemes of national labour force surveys. The proposed methodology, referred to as infinite-lag Markov models, is a generalisation of autoregressive Markov models developed for application in stochastic reservoir theory (Pegram 1980, Raftery 1985). Infinite-lag Markov chains have infinite memory and, therefore, can usefully serve to model labour supply behaviour taking into account, in principle, the complete past work experience of individuals, and not just the most recent past or the most recent spell. After a brief review of the rotation sampling schemes of 20 national labour force surveys, the different types of longitudinal sequences that can be obtained from the rotation schemes are examined. A review of various models proposed in the literature for analysing longitudinal data on employment and unemployment, expressed under simplified assumptions and in discrete forms, set the stage for the formulation of the proposed infinite-lag Markov model. The method is illustrated using matched longitudinal data derived from the US Current Population Survey.     

An integrated corporate planning model for forest-based industries

The paper presents an integrated model for corporate planning of forest-based industries. Techniques are developed to determine the profitability of wood quality manipulations, taking into proper account the impact of uncertainties on future product prices. Production alternatives of final products are specified as functions of wood quality properties which are, in turn, functions of tree type (genotype) alternatives. The total return from processing wood depends on future prices of final products, which are unknown. Selling prices of final products are related to stochastic price indices for solid wood products and paper products. Risk can be reduced by diversifying among genotype alternatives; in a case study the value of a portfolio of genotype alternatives is significantly larger than the single ‘best’ genotype alternative. The model framework may be applicable to any other natural resource industry with similar characteristics such as agriculture, petroleum or mining.     

History of perinatal loss and maternal–fetal attachment behaviors

BackgroundMaternal–fetal attachment (MFA) is an important requirement for optimal maternal–infant adaptation. Current studies showed conflicting findings about whether a history of perinatal loss (fetal/neonatal death) affects maternal attachment in pregnancy.Research question“Does a history of perinatal loss affect maternal–fetal attachment behaviors?”MethodsOne hundred women with and without a history of PL were recruited using a convenience method of sampling, from prenatal care services affiliated to Shahid Behesti University of Medical Sciences. Data collected by questionnaires from a convenience sample of multiparous women in the 3rd trimester of pregnancy with no surviving children were compared with data from a selected cohort of primigravid women. The two groups of women were matched for health and literacy. The data collected included demographic characteristics and responses to 24 questions in five groups of behaviors on the Persian version of Cranly's Maternal–Fetal Attachment Scale. Data were analyzed by SPSS 13 and using t, ANOVA, Chi square, Pearson correlation and Mann–Whitney tests.FindingsFinding showed that total score of MFA for women with a history of PL (68.95 ± 9.20%) is not significantly different from this score for women without such a history (71.22 ± 11.75%; p < 0.05). Women with a history of PL had a significantly lower score for a subgroup of behaviors “differentiation of self from fetus” compared to women without of a history of PL (78.25 vs. 83.21%; p < 0.05). But, there were no statistically significant differences between two groups respecting to other subgroups of behaviors between two groups.ConclusionIn this study, a history of pregnancy loss was found to be associated with disturbances in the group of maternal–fetal attachment behaviors related to “differentiation of self from fetus” in a subsequent pregnancy.     

Migration and livelihood constellations: Assessing common themes in the face of environmental change in Somalia and among Agro-Pastoral peoples

Research on migration has become more challenging due to at least four factors: (1) more complex migration traditions; (2) the development of migration economies that engage many types of migrants from ever more social and cultural backgrounds; (3) increasing likelihood of climate change-driven environmental migration; and (4) increasing likelihood of conflict-based migration in some contexts. These developments have shaken economic theories of migration and have encouraged interdisciplinary, methodologically mixed, qualitative and quantitative research and analysis. From a review of the literature, we have gleaned 11 common themes about environmental, economic and conflict migration that we differentiate by process (migration behaviours that are still evolving) and patterns (migration behaviours that have become customary). We then consider how positive and negative dimensions of migration can be captured and represented with close attention to livelihood constellations (multiple economic activities combined by individuals, households and families). Finally, focusing on Somalia and agro-pastoral peoples generally, where recent environmental and conflict migration have been added to decades of economic migration and centuries of seasonal, environmental migration associated with pastoralism, we combine historical and qualitative work to demonstrate the value of a livelihood constellation perspective.