An analysis on document length retrieval trends in language modeling smoothing

Document length is widely recognized as an important factor for adjusting retrieval systems. Many models tend to favor the retrieval of either short or long documents and, thus, a length-based correction needs to be applied for avoiding any length bias. In Language Modeling for Information Retrieval, smoothing methods are applied to move probability mass from document terms to unseen words, which is often dependant upon document length. In this article, we perform an in-depth study of this behavior, characterized by the document length retrieval trends, of three popular smoothing methods across a number of factors, and its impact on the length of documents retrieved and retrieval performance. First, we theoretically analyze the Jelinek–Mercer, Dirichlet prior and two-stage smoothing strategies and, then, conduct an empirical analysis. In our analysis we show how Dirichlet prior smoothing caters for document length more appropriately than Jelinek–Mercer smoothing which leads to its superior retrieval performance. In a follow up analysis, we posit that length-based priors can be used to offset any bias in the length retrieval trends stemming from the retrieval formula derived by the smoothing technique. We show that the performance of Jelinek–Mercer smoothing can be significantly improved by using such a prior, which provides a natural and simple alternative to decouple the query and document modeling roles of smoothing. With the analysis of retrieval behavior conducted in this article, it is possible to understand why the Dirichlet Prior smoothing performs better than the Jelinek–Mercer, and why the performance of the Jelinek–Mercer method is improved by including a length-based prior.

几何中的比例中项问题

以“问题解决”理论为依据,对一类比例中项问题进行提炼,得到一种具有一般意义的模型,它含有某种模式,只要搞清题设、图形和结论之间的联系,或许会使解题思路更加清晰．     

高等职业教育课程模式设置的探讨

通过教学实践提出几种适合高职教育的课程模式:以问题为中心的综合基础课,以任务为中心的技术课程,以技术开发能力培养为中心的设计课程,以及用于提高学生职业适应性的微型课程等。     

开放数据环境下公共信息再利用的经营模式分析

[目的/意义] 开放数据运动改变了公共信息再利用的环境,从信息再利用经营模式分析入手进行分析,有助于全面了解和掌握开放数据环境下公共信息再利用的特点及运行规律。[方法/过程] 通过国内外文献比较和企业开放数据再利用案例分析,深入总结开放数据对公共信息再利用的影响,进而对数据开放前后公共信息再利用经营模式差异进行比较。[结果/结论] 开放数据不仅扩展了公共信息再利用的视野,改变了其市场结构,增强了信息企业的主体地位,而且还推动了企业信息再利用经营模式的创新,促使其盈利方式更加丰富,更加注重用户资源开发,市场结构与企业运营更加精细。     

德国职业教育集团化办学主要模式及特色

德国在发展职业教育集团化办学方面颇有独特之处。概述德国“双元制”、跨企业培训中心和技术转移中心等三个主要的职业教育集团化办学模式,并对它们的特色进行了剖析。     

数字图书馆建设:回顾与展望

本文探讨了数字图书馆建设已取得的成绩及我国数字图书馆发展中面临的主要问题，并指出具有中国特色数字图书馆发展的基本模式。     

青海省区域经济差异与发展模式分析

青海省在近年来经济发展过程中,不仅存在与东、中部地区的差距,而且存在着省内各区域间经济发展水平的差异问题,差异的扩大将影响青海省整体经济水平的提高和宏观经济目标的实现。本文以县为基本的区域单元,运用因子分析方法对青海省区域经济差异进行了实证分析,在此基础上提出了青海省内不同区域的经济发展模式。     

Partnering with Districts to Expand an After-School Maths Club Programme

Abstract

A key intervention of the South African Numeracy Chair Project (SANCP) since 2011 has been the introduction of mathematics (or maths) clubs, which occur in the out-of-school time space. In 2016 the maths club concept was developed into a 15-week Pushing for Progression (PfP) teacher development programme which supports primary school mathematics teachers to run clubs beyond the SANCP local area. Expanding intervention models beyond local schools is imperative in the second phase of the SANCP (2016–2020). Working from a mixed methods methodological approach, the researchers collected pre- and post-data for a 4-operations assessment of the entire PfP programme. In this article they share learner data from one of the nine teachers who participated in the PfP maths club programme in the Uitenhague District, Eastern Cape, South Africa, to illuminate how partnerships between academics, district officials and teachers can enable powerful student learning in the club space. They argue further that within the tightly focused development programme run by teachers in this one district, it is possible for learners to make substantive progress in mathematical proficiency (MP) (especially procedural fluency and conceptual understanding) when comparing scores and learner methods between a pre- and post- assessment.     

So what exactly do you want? What principals mean when they say ‘male role model’

The need for more male role models in young boys’ lives is one of the main reasons underpinning the call for more male teachers in primary schools. However, the exact responsibilities and attributes associated with the term ‘male role model’ have yet to be clearly established. The purpose of this survey of 250 New Zealand primary school principals was to investigate the views of one major group of stakeholders to determine how principals defined male role models and what they considered the specific attributes of that role. The study found that the principals favoured men who exhibit a hegemonic masculinity couched in heterosexual, rugby‐playing, ‘real men’ attributes.