Predicting distances using a linear model: the case of varietal distinctness

Differences between plant varieties are based on phenotypic observations, which are both space and time consuming. Moreover, the phenotypic data result from the combined effects of genotype and environment. On the contrary, molecular data are easier to obtain and give a direct access to the genotype. In order to save experimental trials and to concentrate efforts on the relevant comparisons between varieties, the relationship between phenotypic and genetic distances is studied. It appears that the classical genetic distances based on molecular data are not appropriate for predicting phenotypic distances. In the linear model framework, we define a new pseudo genetic distance, which is a prediction of the phenotypic one. The distribution of this distance given the pseudo genetic distance is established. Statistical properties of the predicted distance are derived when the parameters of the model are either given or estimated. We finally apply these results to distinguishing between 144 maize lines. This case study is very satisfactory because the use of anonymous molecular markers (RFLP) leads to saving 29% of the trials with an acceptable error risk. These results need to be confirmed on other varieties and species and would certainly be improved by using genes coding for phenotypic traits.     

论高海拔地区人类生殖能力的研究:回应霍夫

霍夫的评论表明,那些叙述高海拔缺氧影响人类生育力和生殖能力的文献中弥漫着方法论和概念的迷雾.我们去年的文章主题也谈到了这一点(见<美国人类学家>85:28-49,1983).我们的论文尽力阐述了喜马拉雅山脉的高海拔地区,藏语族群中普遍存在的不同生育力水平,是与某些文献的报道一致的.     

A GENERALIZED EMERSON RECURRENCE RELATION

The Emerson (1968, Biometrics 24 , 695–701) recurrence relation has many important applications in statistics. However, the original derivation applied only to discrete distributions. In the following, a simple derivation is given that generalizes the Emerson recurrence relation to any distribution for which the necessary expectations exist. A modern application is outlined.     

Children of Adolescent Mothers: Cognitive and Behavioral Status at Age Six

The cognitive and behavioral status at age six years of 185 children of adolescent mothers (60.5% boys) were assessed using the mother (CBCL) and teacher (TRF) report forms of the Child Behavior Checklist and the Bracken Basic Concepts Scale. There was evidence for impairment in all areas of functioning. More than half of the sample exceeded the borderline clinical cutoff (T = 60) on either the CBCL or TRF Total Problem score, and nearly half the sample had Bracken scores that were more than 1 SD below the normative mean. Only 26.9% of the children were in the normal range on all three measures. These results are discussed in terms of implications for social work practice with children and adolescent mother families.     

Gender Competition and the Preservation of Community in the Allocation of Administrative Positions in Small Rural Towns in Montana: A Research Note1

Abstract Assignment of administrative positions in a sample of rural towns is demonstrated to be significantly associated with gender. Most civil administrators are women, while most legal and educational administrators are men. The difference indicates structural assignment of positions by gender. Gender and administrative position are demonstrated to have zero-order correlations with perceptions of two important behaviors for community: migration and social problems. The characteristics of the occupation and of the administrators are qualitatively different. The data are compiled from interviews with seventy administrators in five pairs of small towns in Montana, ranging in size from about 200 to approximately 7,000 residents. Each pair contains one agricultural and one scenic recreational town. Comparatively, more women were employed in agricultural towns. Many rural women who become administrators, particularly long-term administrators, may be selected for reasons that help preserve the community by providing opportunities for themselves and their families.     

Interparental Conflict and Preschoolers' Peer Relations: The Moderating Roles of Temperament and Gender

The relations between destructive interparental conflict (IPC) and three‐ to six‐year‐olds’ (N = 62) peer relations were examined as a function of child temperament and gender. Regression analyses indicated that effortful control moderated the relations of IPC with children's amount of peer interaction as well as with their problematic relations with peers. Specifically, high IPC was associated with low amount of interaction and high problematic relations for preschoolers low in effortful control, but it was related to high amount of interaction and low problems for those high in effortful control. Additionally, gender differences in the relations between IPC and the amount of peer interaction indicated that IPC was negatively related to the amount of interaction for girls but positively related to the amount for boys. The findings highlight the need for examining individual differences in the relations between IPC and the development of early peer relations.     

The Safeguarding Effect of Governance Mechanisms in Inter‐firm Exchange: The Decisive Role of Mutual Opportunism

This study empirically investigates the safeguarding effect of (1) administrative control, (2) a dominant power position and (3) relational norms, on opportunistic behaviour of suppliers, by means of a survey among 624 information and communication technology professionals in Dutch municipalities. The findings indicate that individual effectiveness of relational norms, particularly in terms of flexibility and solidarity, was most prominent. Administrative control and power did not show a significant impact on supplier opportunism in our sample. Research into the simultaneous use of several safeguards against opportunism generated the finding that different relational norms fortify each other's safeguarding effect. Furthermore, we demonstrate that supplier opportunism is only mitigated by a dominant power position when the buyer does not exploit its favourable position and the buyer does not behave opportunistically. Hence, power seems to have a safeguarding effect only when it is not used.     

Estimating Individual-Level Risk in Spatial Epidemiology Using Spatially Aggregated Information on the Population at Risk

We propose a novel alternative to case-control sampling for the estimation of individual-level risk in spatial epidemiology. Our approach uses weighted estimating equations to estimate regression parameters in the intensity function of an inhomogeneous spatial point process, when information on risk-factors is available at the individual level for cases, but only at a spatially aggregated level for the population at risk. We develop data-driven methods to select the weights used in the estimating equations and show through simulation that the choice of weights can have a major impact on efficiency of estimation. We develop a formal test to detect non-Poisson behavior in the underlying point process and assess the performance of the test using simulations of Poisson and Poisson cluster point processes. We apply our methods to data on the spatial distribution of childhood meningococcal disease cases in Merseyside, U.K. between 1981 and 2007.