Motherhood status and union formation in Moshi,Tanzania 2002–2003

Age at first union is increasing throughout much of sub-Saharan Africa at the same time that not all couples are waiting for marriage before their first sexual intercourse. We assessed the effect of a premarital first birth on entrance into a first union in an urban area in East Africa—Moshi, Tanzania. The data come from the Moshi Infertility Survey of 2002–2003. Women who spent less than a year in single motherhood were significantly more likely than childless women to enter into a first union, although the magnitude of this relationship was weaker for more recent cohorts. Women who had been single mothers for 5 or more years (about two-thirds of women with a premarital birth) were significantly less likely than women without children to enter into a first union.     

Vertical foodweb structure of freshwater zooplankton assemblages estimated by stable nitrogen isotopes

Although theoretical foodweb models predict the presence of only three to four trophic categories, estimation of “potential” vertical foodweb structure from species lists and inferred feeding interactions suggest that as many as 7 trophic categories can occur in the pelagic foodwebs of North American glaciated lakes. A compilation of data on the nitrogen isotopic composition of zooplankton from 46 Canadian Shield lakes suggested the average existence of one “realized” trophic category in addition to that of filter-feeding, herbivorous cladocerans. When phytoplankton, planktivorous invertebrates, and plantivorous and piscivorous fish are included, the vertical foodweb structure in the pelagic zones of these lakes are greater than those hypothesized from some theoretical models.     

Demographic change and response: Social context and the practice of birth control in six countries

This paper expands on Kingsley Davis’s demographic thesis of change and response. Specifically, we consider the social context that accounts for the primacy of particular birth control methods that bring about fertility change during specific time periods. We examine the relevance of state policy (including national family planning programs), the international population establishment, the medical profession, organized religion, and women’s groups using case studies from Japan, Russia, Puerto Rico, China, India, and Cameroon. Some of these countries are undergoing the second demographic transition, others the first. Despite variations in context, heavy reliance on sterilization and/or, abortion as a means of birth control is a major response in most of these countries. The key roles of the medical profession and state policy are discussed, along with the general lack of influence of religion and of women’s groups in these countries.     

Comparative well being of Israeli youngsters in residential care with and without siblings

This paper presents the findings of a study comparing the well being and self-esteem of young adolescents (age 12-14) who were placed together with their siblings in residential facilities (intact care) in Israel and of youngsters who were placed without their siblings (separate care). The study examines the contribution of sibling relations, frequency of the meetings between the siblings, parental favoritism, age rank, time in care, self-esteem and perception of parents' economic status to the well being of the youngsters in the two groups. The findings show that the youngsters in intact care (N = 91) reported greater well being than those in separate care (N = 103), but have no other significant differences. Greater self-esteem and sibling closeness improved the well being of both groups of youngsters, but the other predictor variables functioned differently in the two groups. Greater frequency of meetings improved the well being only of the youngsters in intact care, while the other variables examined improved the well being only of those in separate care. Moreover, the examined variables accounted for a greater proportion of the variance in the youngsters' well being when the sibling was absent than when he or she was present. Practical implications are suggested.     

Nonlinear structural equation modeling: is partial least squares an alternative?

Nonlinear structural equation modeling provides many advantages over analyses based on manifest variables only. Several approaches for the analysis of latent interaction effects have been developed within the last 15 years, including the partial least squares product indicator approach (PLS-PI), the constrained product indicator approach using the LISREL software (LISREL-PI), and the distribution-analytic latent moderated structural equations approach (LMS) using the Mplus program. An assumed advantage of PLS-PI is that it is able to deal with very large numbers of indicators, while LISREL-PI and LMS have not been investigated under such conditions. In a Monte Carlo study, the performance of LISREL-PI and LMS was compared to PLS-PI results previously reported in Chin et al. (2003) and Goodhue et al. (2007) for identical conditions. The latent interaction model included six indicator variables for the measurement of each latent predictor variable and the latent criterion, and sample size was N=100. The results showed that PLS-PI’s linear and interaction parameter estimates were downward biased, while parameter estimates were unbiased for LISREL-PI and LMS. True standard errors were smallest for PLS-PI, while the power to detect the latent interaction effect was higher for LISREL-PI and LMS. Compared to the symmetric distributions of interaction parameter estimates for LISREL-PI and LMS, PLS-PI showed a distribution that was symmetric for positive values, but included outlying negative estimates. Possible explanations for these findings are discussed.     

Competitive and Cooperative Positioning in Supply Chain Logistics Relationships*

Cooperative logistics relationships require the sharing of information, which must be enabled by the integration of disparate information systems across partners. In this article, we theorize business‐to‐business logistics relationships should be managed using cooperative and competitive postures. Based on data from 91 dyadic relationships using interorganizational information technology (IT), we find that performance gains accrue when parties share strategic information and customize IT; mutual trust enables IT customization and strategic‐information flows and equitable relationship‐specific investments positively impact IT customization, mutual trust, and performance. Among other scholarly and practical implications discussed, partners should compete on resources for IT customization and cooperate to share strategic information. Managers tend to think of relationships with firms as polar opposites and view them as entirely cooperative or entirely competitive. Our results support active balancing and understanding of both competitive and cooperative stances. Such an approach enables conditions for participation symmetry that yields greater performance gains.