医学文献检索总论概述研究生教学课件.ppt

检索效果的评价 用户相关性 判断 系统匹配性判断 相关文献 非相关文献 总计 被检出文献 a（命中） b（误检） a+b 未检出文献 c（漏检） d（正确拒绝） c+d 总计 a+c b+d a+b+ c+d 查全率（R）= a/(a+c)*100% 查准率（P）= a/(a+b)*100% 概 述 谢 谢！ * This is often referred to as the evidence pyramid. It is used to illustrate the evolution of the literature. The base of the pyramid is where information usually starts with an idea or laboratory research. As these ideas turn into drugs and diagnostic tools they are tested in laboratories models, then in animals, and finally in humans. The human testing may begin with volunteers and go through several phases of clinical trials before the drug or diagnostic tool can be authorized for use within the general population. Randomized controlled trials are then done to further test the effectiveness and efficacy of a drug or therapy. As you move up the pyramid the amount of available literature decreases, but increases in its relevance to the clinical setting. Meta-Analysis takes the systematic review (see below) a step further by using statistical techniques to combine the results of several studies as if they were one large study. Systematic Reviews usually focus on a clinical topic and answer a specific question. Extensive literature searches are conducted to identify studies with sound methodology. The studies are reviewed, assessed, and summarized according to the predetermined criteria of the review question. Randomized Controlled Trials are carefully planned projects that study the effect of a therapy or test on real patients. They include methodologies that reduce the potential for bias and that allow for comparison between intervention groups and control groups (no intervention). Evidence for questions of diagnosis is found in prospective trials which compare tests with a reference or gold standard test. Cohort Studies take a large population and follow patients who have a specific condition or receive a particular treatment over time and compare them with another group that is s