医学科研中样本量的估算方法介绍

正样本含量估计一直是医学科研设计中的一道难题,大部分科研人员还没有清楚认识样本含量估计的重要性,样本量过大会造成资料浪费,样本量过小则统计效能不高。现介绍几种样本量估算工具,可以帮助医学科研人员方便进行样本量的估算。1PASS软件PASS软件需要下载安装在计算机上,是样本量估算和效能分析的专业统计软件,能对多种统计学检验下的样本含量和     

临床研究中样本量的估计方法

重点介绍临床研究中样本含量的估计条件,阐述一些常用的样本含量的估计方法,其中着重介绍了定量反应资料样本含量的计算方法,定性反应资料样本含量的计算方法以及直线相关研究样本量的估计方法。     

样本含量

<正>样本含量(sample size)即观察单位数,又称样本大小。在保证研究结论具有一定可靠性(精确度和检验效能)的前提下,常需要在设计阶段就认真估计最少的受试对象数。正确估计样本含量是实验设计的一个重要组成部分。样本含量估计充分反映了实验设计中"重复"的基本原则,过小过大都存在弊端。     

科研设计与护理论文撰写

第一节科研设计三、科研设计的统计学原则(二)重复(replication) 重复的原则足指实验的次数或观察的例数。在抽样研究中,每个样本所包含的调查或受试对象数称为样本含量。在科研设计中要重视样本含量问题。由于生物的个体差异很大,样本含量过少,就不能代表总     

何为完全随机设计

完全随机设计（completely random design）又称单因素设计,或成组设计,是医学科研中最常用的一种研究设计方法,它是将同质的受试对象随机地分配到各处理组中进行实验观察,或从不同总体中随机抽样进行对比研究。改设计适用面广,不受组数的限制,且各组的样本含量可以相等,也可以不相等,但在总样本量不变的情况下,各组样本量相同时设计效率最高。     

日立7060型全自动生化分析仪盘号的巧妙应用

我们用日立7060全自动生化分析仪进行样本的常规操作时，发现当样本量超过每盘的最大位置号(50)时，在输入下一个样本号时(例51、101等)．仪器的盘号将自动进1。而在操作时，当每加完一盘的样本时，仪器就会自动停止加样，等待换盘，然后需要再次按开始键。换盘和启动到加下一盘的样本需大约20min．这对我们快速的检验实在不     

反应体系对荧光定量PCR检测乙肝核酸结果影响的分析

目的探讨荧光定量PCR检测乙型肝炎病毒核酸（HBV-DNA）时核酸提取体系中加入样本量的不同和不同反应体系对检测结果的影响。方法选取乙肝检测患者DNA定量结果为低拷贝数（10-103copies/ml）和高拷贝数（105-107copies/ml）样本各10例,分别按2种核酸提取体系及2种反应体系分为4组进行HBV-DNA荧光定量PCR检测。结果 10例低拷贝数样本减少反应体系后只有3例检出有反应,由于反应体系的减小造成结果存在明显差异,P〈0.01;即使增加提取核酸时加入的样本量,结果仍然存在差异,P〈0.01。10例高拷贝数的样本改变提取核酸时加入的样本量及最终的反应体系,各组的算术平均值在0.43-2.31倍之间,数量级变化〈1。结论反应体系过小会造成低拷贝数样本出现假阴性,所以要保证反应体系中加入足够的提取出的核酸以确保样本HBV-DNA的检出率。     

GRADE指南:Ⅴ.证据质量评价——发表偏倚

GRADE方法中,随机试验起评即为高质量证据,观察性研究起评即为低质量证据;但若证据本身存在高发表偏倚风险,则两者证据质量级别都应降低。即使最佳证据汇总表纳入的各项研究仅有低发表偏倚风险,发表偏倚仍会极大高估效应值。当可得证据来自小样本研究、且多数由厂商资助时,作者应怀疑存在发表偏倚。若干基于检验数据类型的方法可用于评价发表偏倚,其中最常用的为漏斗图,但这些方法都有较大局限。发表偏倚可能较常见,必须特别关注早期结果、对样本量与事件数都很小的早期试验结果尤需小心。     

131I 治疗131I全身显像阴性/甲状腺球蛋白阳性的分化型甲状腺癌临床研究的方法学质量评价

目的评价目前131I 治疗131I全身显像阴性(131I WBS-)、甲状腺球蛋白阳性(Tg )的分化型甲状腺癌临床研究论文的方法学质量.方法计算机检索MEDLINE(1966～2004.3)、EMBASE(1984～2003)、Cochrane图书馆临床对照试验资料库(2004年第2期)、中国生物医学文献光盘数据库(1978～2004.6)和中国学术期刊全文数据库(1994～2004),同时手检<同位素>等5种放射治疗和内分泌杂志(1980.1～2003.4).采用Cochrane系统评价指南的质量评价标准,对收集到的所有临床对照研究文献的质量进行评价.结果未检索到随机对照试验,检索到非随机对照研究3篇,其中前瞻性非随机对照研究2篇,历史对照研究1篇.3个研究的样本含量分别为26、60和70例,组间样本含量不等,均未说明所取样本量的依据;组间基线相似性不一;均未在治疗实施和疗效评价中采用盲法评价疗效;随访时间2～15年,均未报道131I 治疗的不良反应;未报道失访病例.2个研究的统计方法使用正确,另一个研究运用的统计方法模糊.结论 131I 治疗131I WBS-/Tg 的分化型甲状腺癌缺乏随机对照试验,临床对照研究论文的质量在随机、双盲、随访、样本含量等方面存在一些问题,有待进一步改进.目前迫切需要高质量的临床对照研究和RCT.     

实验设计中样本含量估算方法探讨——以PI3K抑制剂对小鼠气道炎症影响的实验研究为例

目的介绍和比较医学实验设计中不同的样本含量估算方法。方法以磷酸酰肌醇-3激酶(PI3K)抑制剂对小鼠气道炎症影响的实验研究为例,运用不同方法计算样本含量。结果公式法计算需12只,PASS软件Simple法计算需8只,Stata软件计算需10只,验算其检验效能:1-β0.9。结论 3种不同方法估算的样本含量都是合理有效的,实验研究人员可以以多种计算结果为依据,分析实验研究性质,综合考虑研究成本、可行性与伦理学要求对样本含量的影响,确定合适的样本数。     

Guns and Knives in New Mexico: Patterns of Penetrating Trauma, 1978–1993

Objective: To identify patterns of nonfatal and fatal penetrating trauma among children and adults in New Mexico using ED and medical examiner data.
Methods: The authors retrospectively sampled in 5-year intervals all victims of penetrating trauma who presented to either the state Level-1 trauma center or the state medical examiner from a 16-year period (1978–1993). Rates of nonfatal and fatal firearm and stabbing injury were compared for children and adults.
Results: Rates of nonfatal injury were similar (firearm, 34.3 per 100,000 person-years; stabbing, 35.1). However, rates of fatal injury were significantly different (firearm, 21.9; stabbing, 2.7; relative risk: 8.2; 95% confidence interval: 5.4, 12.5). From 1978 to 1993, nonfatal injury rates increased for children (p = 0.0043) and adults (p < 0.0001), while fatal penetrating injury remained constant. The increase in nonfatal injury in children resulted from increased firearm injury rates. In adults, both stabbing and firearm nonfatal injury rates increased.
Conclusions: Nonfatal injury data suggest that nonfatal violence has increased; fatal injury data suggest that violent death rates have remained constant. Injury patterns vary by age, mechanism of trauma, and data source. These results suggest that ED and medical examiner data differ and that both are needed to guide injury prevention programs.     

Dissociable correlates of two classes of retrieval processing in prefrontal cortex

Although substantial evidence suggests that the prefrontal cortex (PFC) implements processes that are critical for accurate episodic memory judgments, the specific roles of different PFC subregions remain unclear. Here, we used event-related functional magnetic resonance imaging to distinguish between prefrontal activity related to operations that (1) influence processing of retrieval cues based on current task demands, or (2) are involved in monitoring the outputs of retrieval. Fourteen participants studied auditory words spoken by a male or female speaker and completed memory tests in which the stimuli were unstudied foil words and studied words spoken by either the same speaker at study, or the alternate speaker. On "general" test trials, participants were to determine whether each word was studied, regardless of the voice of the speaker, whereas on "specific" test trials, participants were to additionally distinguish between studied words that were spoken in the same voice or a different voice at study. Thus, on specific test trials, participants were explicitly required to attend to voice information in order to evaluate each test item. Anterior (right BA 10), dorsolateral prefrontal (right BA 46), and inferior frontal (bilateral BA 47/12) regions were more active during specific than during general trials. Activation in anterior and dorsolateral PFC was enhanced during specific test trials even in response to unstudied items, suggesting that activation in these regions was related to the differential processing of retrieval cues in the two tasks. In contrast, differences between specific and general test trials in inferior frontal regions (bilateral BA 47/12) were seen only for studied items, suggesting a role for these regions in post-retrieval monitoring processes. Results from this study are consistent with the idea that different PFC subregions implement distinct, but complementary processes that collectively support accurate episodic memory judgments.     

Interprofessional approaches to creating safe,high quality health care

Three supplementary perspectives are presented arguing that interprofessional collaboration is both necessary and desirable. Nonetheless, there are often too many serious intra-professional barriers and obstacles to interprofessional collaboration to make it successful. Some of these barriers, it is argued and illustrated, are found in the multiple ways in which professional identity is tacitly acquired and embodied in the practitioners' habitual, everyday practice. The paper then explores ways in which reflection, especially Second order reflection, can help to elucidate and overcome these obstacles, as well as increasing professional adaptability and competence.     

Systematic Reviews Published in the January 2011 Issue of The Cochrane Library

ABSTRACT

The Cochrane Library of Systematic Reviews is published quarterly as a DVD and monthly online. The January 2011 issue (first quarterly DVD for 2011) contains 4515 complete reviews, 1985 protocols for reviews in production, and 13,521 one-page summaries of systematic reviews published in the general medical literature. In addition, there are citations of 641,000 randomized controlled trials, and 14,018 cited papers in the Cochrane methodology register. The health technology assessment database contains over 9300 citations. One hundred and seven new reviews have been published in the last 3 months, of which five have potential relevance for practitioners in pain and palliative medicine.     

Modified micro-superior percutaneously-assisted total hip: early experiences & case reports

Because of the extensile nature and familiarity of the standard posterior-lateral approach to the hip, a family of "micro-posterior" approaches has been developed. This family includes the Percutaneously-Assisted Total Hip (PATH) approach, the Supercapsular (SuperCap) approach and a newer hybrid approach, the Supercapsular Percutaneously-Assisted Total Hip (SuperPATH) approach. Such approaches should ideally provide a continuum for the surgeon: from a "micro" (external rotator sparing) posterior approach, to a "mini" (external rotator sacrificing) posterior approach, to a standard posterior approach. This could keep a surgeon within his comfort zone during the learning curve of the procedure, while leaving options for complicated reconstructions for the more practiced micro-posterior surgeons. This paper details one author's experiences utilizing this combined approach, as well as permutations of this entire micro-posterior family of approaches as applied to more complex hip reconstructions.     

Determination of creatine kinase isoenzyme MB activity in serum using immunological inhibition of creatine kinase M subunit activity. Activity kinetics and diagnostic significance in myocardial infarction.

This is a new method for the determination of creatine kinase isoenzyme MB activity in serum. The method uses direct activity measurement of creatine kinase B subunit activity after blocking of CK-M subunit activity by inhibiting antibodies. The test takes no longer than 15 min. The method yields an intra-serial C.V. of 2.0-12.9%, and a C.V. from day to day of 5.5%. The detection limit is 3.4 U/l creatine kinase MB. In the 95 cases with proven myocardial infarction several types of creatine kinase MB activity kinetics could be determined. The percentage of creatine kinase MB of peak CK-total is 6-25%, with a mean of 11.1%. The amount of creatine kinase MB with respect to total CK activity after reinfarction is higher than the amount after initial infarction.     

Structure and function of "metalloantibiotics"

Although most antibiotics do not need metal ions for their biological activities, there are a number of antibiotics that require metal ions to function properly, such as bleomycin (BLM), streptonigrin (SN), and bacitracin. The coordinated metal ions in these antibiotics play an important role in maintaining proper structure and/or function of these antibiotics. Removal of the metal ions from these antibiotics can cause changes in structure and/or function of these antibiotics. Similar to the case of "metalloproteins," these antibiotics are dubbed "metalloantibiotics" which are the title subjects of this review. Metalloantibiotics can interact with several different kinds of biomolecules, including DNA, RNA, proteins, receptors, and lipids, rendering their unique and specific bioactivities. In addition to the microbial-originated metalloantibiotics, many metalloantibiotic derivatives and metal complexes of synthetic ligands also show antibacterial, antiviral, and anti-neoplastic activities which are also briefly discussed to provide a broad sense of the term "metalloantibiotics."