Statistics in Latin America

Statistics is a relatively new discipline in Latin America. At present only sparse information is available about the state of the statistical profession in Latin America. We present and summarize the available information about the job market; training, education, and research; professional societies and their activities; and so forth. We also share our hopes, concerns, and suggestions for the future.     

The sample monomode and an associated test for discrete monomodality

Abstract

The notions of (sample) mean, median and mode are common tools for describing the central tendency of a given probability distribution. In this article, we propose a new measure of central tendency, the sample monomode, which is related to the notion of sample mode. We also illustrate the computation of the sample monomode and propose a statistical test for discrete monomodality based on the likelihood ratio statistic.     

Bernoulli Processes with Non-Positive Correlations

We deal with sequences of dependent Bernoulli variables with non positive correlations. Some special models for 1-dependent and 2-dependent 0–1 valued variables are analyzed, namely Bernoulli variables obtained by clipping a linear combination of iid variables. Formulas describing dependence of their correlation function on the clipping parameters are derived. The lower bound for the sum of autocorrelations of Bernoulli variables obtained by clipping a Gaussian process is provided.     

A hierarchy of lorenz curves based on the generalized tukey's lambda distribution

A hierarchy of Lorenz curves based on the generalized Tukey's Lambda distribution is proposed. Representations of the corresponding distribution and density function are also provided, together with popular inequality measures. Estimation methods are suggested. Finally, a comparison with other parametric families of Lorenz curves is established.     

Estimation in capture–recapture models when covariates are subject to measurement errors and missing data

For capture–recapture models when covariates are subject to measurement errors and missing data, a set of estimating equations is constructed to estimate population size and relevant parameters. These estimating equations can be solved by an algorithm similar to the EM algorithm. The proposed method is also applicable to the situation when covariates with no measurement errors have missing data. Simulation studies are used to assess the performance of the proposed estimator. The estimator is also applied to a capture–recapture experiment on the bird species Prinia flaviventris in Hong Kong. The Canadian Journal of Statistics 37: 645–658; 2009 © 2009 Statistical Society of Canada     

交易费用、农地流转与新一轮农地制度改革——基于苏、桂、鄂、黑四省区农户调查数据的分析

农地流转是促进农地规模经营的必经之路,已成为新一轮农地制度改革的中心议题。基于江苏、广西、湖北及黑龙江四省区农户调查数据的实证分析结果显示,交易费用是影响农地流转的一个重要约束因素,农地流转中存在的交易费用既抑制转入户转入土地,又抑制转出户转出土地。因此,新一轮农地制度改革进程中应全面降低农地流转面临的各类交易费用,促进农地经营权规范有序流转,发展农业适度规模经营。     

紧固件自动涂胶设备关键结构设计

针对紧固件手工方式涂胶存在的加工效率低、涂胶不均匀、胶液浪费等问题,本文对紧固件自动涂胶设备进行了 开发设计。采用螺旋槽式输料结构,实现了零件的自动排序和上料;设计了由间隙可调式导轨、气动系统和分离圆盘组 成的驱动机构;利用配合运动的方式,设计了紧固件的涂胶机构,包括涂胶片、摆动臂、旋转电机、顶推套筒及驱动气缸, 实现了对排序零件的自动连续涂胶。结果表明该设备自动化程度较高,零件加工范围广,涂胶均匀,同时避免了手工涂 胶对人体产生的伤害。     

陶瓷零件快速成型机的改进设计

在层和速凝技术原理的基础上,研制出一种适合陶瓷零件的快速成型设备,但该设备存在刚性不足,变形较大等问题,为了解决该问题,对铺料台升降装置进行了改进,将铺料台单边支撑改为中间对称支撑方式,改进后的陶瓷零件快速成型机加强了运行的可靠性和平稳性。在此基础上对设备的的特点、技术参数和适用范围进行了说明,并以制备95A1203陶瓷凸轮件为例,对成型过程进行了实验,得到成型样品,在电镜下进行SEM测试,结果表明：烧结后样品层间无分层迹象,说明样品已经烧结为一体,材料黏合程度符合要求;与传统陶瓷零件成型设备相比,新型陶瓷件快速成型机提高了加工效率,降低了生产成本,达到了经济实用的目的。     

入世后政府必须尽快转变职能

转变政府职能 ,实现职能创新 ,是应对入世的迫切需要。政府应规范自身行为 ,依法行政 ,让权力在阳光下透明运行 ;政府应改革行政审批制度 ,收缩范围 ,减少环节 ,高效行政 ;政府应增强公共管理职能 ,在维护本国利益 ,整顿与规范市场秩序 ,关心与扶植弱势群体等方面 ,到位行政