首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 85 毫秒
1.
为保证研究结果的准确,在研究设计初始,样本含量估算具有重要意义,合适的样本含量有助于研究者用最合理的资源获得最可靠的研究结果或发现有意义的临床差异。针对不同的研究问题,不同的研究方法,对样本含量的要求也就不同。但在估算样本含量时,均需要参考的3个标准是:研究个体的变异度、研究结果的精确度(抽样误差)和把握度。此外,对常用的样本含量估算方法(公式计算法、查表法和文献法或专家咨询)进行归纳,并提出在以上基础上,还需考虑研究成本、可行性与伦理学要求对样本含量的影响。本研究主要以脑血管病研究为例,介绍样本含量的计算方法。  相似文献   

2.
合理的样本量估计是临床研究设计的重要环节,也是临床医师进行科研设计需关注的重 要问题之一。临床研究的样本量估计与研究目的、研究设计、主要观察指标的资料类型、效应值、变 异度、检验水平和把握度等因素有关。临床研究设计中样本量估计的常见错误包括未经过计算直接 确定样本量、样本量估算方法与研究设计和主要观察指标不对应,参数设置不合理等。  相似文献   

3.
明确阐释在进行精神卫生临床试验设计时,应正确把握"重复原则"的意义和要领。从基本常识出发,并基于精神卫生科研的特点,寻找和发现在此研究领域中,怎样做才能被称为严格遵守了"重复原则"。通过结合本专业的特点,并结合实例,获得如下的结果,即在进行精神卫生临床试验设计时,必须把握好以下四个方面:1正确领悟重复的三层涵义;2正确领悟什么是独立重复试验;3应清楚估计样本含量需要满足哪些前提条件;4应至少学会用一种统计软件方便快捷地估计出合适的样本含量。在如何严格遵守重复原则问题上,正确把握好前述提及的四个方面,就是抓住了问题的本质,是提高临床试验研究质量的一个重要环节。  相似文献   

4.
本文目的是介绍医学科研设计方法中的几个关键性内容,为实际科研工作者进行医学科研提供基本思路。首先,归纳和总结出医学科研课题的五大类,即非临床试验研究课题、临床试验研究课题、观察性研究课题、文献研究课题和真实世界研究课题。其次,呈现出医学科研设计架构,即由"设计方案""实施方案"和"结题方案"三个主方案组成,它们又可被细分为六个子方案。第三,介绍了临床试验研究注册方面的内容,涉及到何为临床试验研究注册及其意义和具体的注册方法。  相似文献   

5.
本文的目的是使读者能方便快捷地运用SAS软件中的POWER过程和GLMPOWER过程实现样本含量估计。在不同的场合下估计样本含量需要提供不同的前提条件,即使仅限于假设检验时估计样本含量,也必须进一步弄清对应的设计类型、结果变量的性质、某些先验知识和对结果精确度的要求。本文通过一些实例,介绍了估计样本含量与检验效能的SAS实现方法。读者只需要修改本文中所呈现的SAS程序中的少量参数,就可方便地使用SAS软件实现样本含量与检验效能估计。事实说明,尽管SAS软件非常难学难用,但借助现成的SAS程序,读者可以轻松自如地解决很多与统计分析有关的具体问题。  相似文献   

6.
本文目的是使读者快速掌握用R软件估计样本含量和检验效能的方法。通过R软件中的stats包中的三个函数,即power.t.test()、power.prop.test()和power.anova.test(),可以很方便地估计若干种场合下的样本含量或检验效能。事实表明:R软件易于获取、易学易用、功能强大、适用面宽,可以方便快捷地解决试验设计中的样本含量与检验效能估计问题。  相似文献   

7.
我们通常采用卡方检验或Fisher精确检验处理结果为二值变量的单因素两水平设计定性资料(也称为四格表资料),这些方法属于差异性检验。在新药或医疗器械临床试验研究中,还可能需要采用非劣效性检验、等效性检验、优效性检验这3种特殊的假设检验方法中的某一种来处理此类资料。上期讲座中,我们介绍了结果为定量变量的单因素两水平设计三种特殊检验的样本含量估计,本期向读者介绍结果为二值变量的单因素两水平设计三种特殊检验的样本含量估计。  相似文献   

8.
在2011年第4期和第5期的讲座中,我们介绍了成组设计三种特殊检验的样本含量估计问题,本期讲座中将为读者介绍成组设计定量资料和定性资料差异性检验的样本含量估计。所谓差异性检验,研究目的是分析两组样本所代表的两个总体均数(或总体率)是否相等。对于定量资料,若资料满足参数检验的前提条件(独立性、正态性和方差齐性),可采用成组设计定量资料检验进行分析;否则,需要采用秩和检验。对于定性资料,可采用卡方检验或Fisher精确检验进行分析。  相似文献   

9.
在观察防治性措施效应的过程中 ,会受到各种影响因素的干扰。因此 ,为了要确定防治措施的真实效果 ,必须对有关影响因素加以控制 ,尽可能清除它们对研究工作的影响。1.可比性 :从选择观察对象及研究方案开始时 ,研究基线状况应保持相对平衡 ,增强其可比性。如果在观察开始前 ,两组就存在差异 ,必能对最后的结果产生严重的影响。临床防治和研究中 ,可采用配对分层后随机分配分组等方法 ,用严格纳入与排除标准选择合格的研究对象等 ,以维持可比性。2 .样本大小 :样本量过小 ,发生机遇的可能性要大一些 ,结论的可信性方面 ,通常比大样本研究的…  相似文献   

10.
医学期刊中常见的统计学错误及对策   总被引:3,自引:0,他引:3  
在医学期刊的论文中,一个不可回避的问题是统计学应用水平如何。因为生物医学科研的对象是具有极大变异性的生物体,而要研究具有变异性的事物或现象的变化规律,是绝对离不开统计学的。可以这样说,统计学运用的质量高低是反映一篇生物医学科研论文科学性与严谨性的一面镜子,是反映一项生物医学科研课题的  相似文献   

11.
The comparative effectiveness of the inhibitory influence of tetanic stimulation of hypothalamus, amygdala and limbic cortex on EMG-response of m. digastricus evoked by electrical stimulation of tooth pulp nociceptive afferents was studied in cats anesthetized with a mixture of chloralose and nembutal. It was found that inhibition of the EMG-component of the jaw-opening reflex is most pronounced in case of stimulation of medial and lateral region of the hypothalamus, the inhibitory effect of central and medial nuclei of the amygdala is less pronounced and the effect of the limbic cortex is the weakest. It was shown that the mechanism of the antinociceptive effect of tetanic stimulation of the hypothalamus is not related to the concomitant increase of the blood pressure. After stabilization of the blood pressure the suppressive effect of the hypothalamus remains without changes, that points out to a direct, primary, not baro-afferent mechanism of the inhibition of the activity of nociceptive neurons of the trigeminal sensory nuclei. Noradrenaline, injected intravenously, induced a large increase of the blood pressure accompanied by a pronounced inhibition of the pain reflex. Angiotensin causes the same degree of blood pressure elevation without changes in the amplitude of the EMG-response of the pain reflex. Hypothalamic and noradrenergic mechanisms for control of pain sensitivity are discussed.  相似文献   

12.
13.
14.
15.
药物治疗与合并认知行为治疗对强迫症疗效的比较   总被引:2,自引:0,他引:2  
目的探讨认知行为心理治疗(CBT)在强迫症(OCD)患者各亚型治疗中的有效性和规律性。方法本研究为临床对照研究。符合入组标准的强迫症患者按患者自愿原则分为两组,治疗观察3、6、12个月。疗效评定分别运用Yale-Brown强迫量表,自拟的自评好转程度量表和临床疗效评定。结果认知行为心理治疗合并药物治疗组31例,临床有效率70.9%,其中治愈率1.8%。单纯药物治疗组24例,临床有效率33.3%。Yale-Brown强迫量表和自评量表得分在6个月和12个月两组有显著差异(P<0.05)。其中强迫症亚型(怕脏型、反复检查型和反复担心型)的疗效比较,怕脏型在治疗3个月末两组间自评量表评分有显著性差异(P<0.05);反复担心型在治疗6个月末两组间Yale-Brown强迫量表总分有显著性差异(P<0.05);反复检查型两组间无统计学差异。结论认知行为心理治疗合并药物治疗强迫症的疗效明显优于单纯药物治疗。强迫症的亚型在治疗中的有效性次序为:反复担心型>怕脏型>反复检查型。  相似文献   

16.
Summary Vasomotor responses from the nasal mucosa and tongue, and contractions of the nictitating membrane, were recorded on stimulation of the cervical sympathetic or internal carotid nerves.Preganglionic sympathetic nerve fibres which elicited a membrane response possessed a lower threshold than those which evoked nasal vasoconstriction, while the latter displayed a lower threshold than fibres which evoked tongue vasoconstriction. The sympathetic vasodilator fibres to the tongue, whose activity was revealed after-receptor blockade, had a similar threshold to the vasoconstrictor fibres.Membrane contraction, nasal vasoconstriction and occasionally tongue vasoconstriction could be evoked by stimulating the internal carotid nerve. The postganglionic fibres innervating the nasal mucosa had a similar threshold to those of the nictitating membrane, which may indicate that there are small myelinated fibres innervating the mucosa.The preganglionic compound nerve action potential had four major components, S1–S4. S1, S2 and usually S3 fibres were associated with membrane contraction; S2, S3 and sometimes S1 fibres were associated with nasal vasoconstriction; and S3, usually S2 and occasionally S1 fibres were associated with vasoconstriction in the tongue. It is concluded that each of these three groups of nerve fibres, but not S4 fibres, may include fibres associated functionally with the three effectors.There was a considerable difference between the relative amplitude of the responses of the three effectors elicited by stimulation of the cervical sympathetic nerve at frequencies between 0.2 and 2 Hz. Vasoconstrictor responses were relatively larger than membrane contractions suggesting differences in the mechanisms of neurotransmission at the neuroeffector junctions.  相似文献   

17.
18.
Summary The distribution of aminergic and non-aminergic nerve fibres to the different constituents of the wall of the digestive tract in various regions is described. Aminergic fibres synapse with all nervous perikarya. Densely interlacing networks of nerve fibres are found in both layers of the tunica muscularis and in the lamina muscularis mucosae. A finely meshed plexus is observed in relation to the wall of the blood vessels in the wall of the gut. There are many fibres connecting the muscular and the vascular plexus. No nerve fibres have been observed in direct relation to the epithelium.The functional implications of these findings are discussed.  相似文献   

19.
Neurons in the deeper layers of the superior colliculus (SC) have spatially tuned receptive fields that are arranged to form a map of auditory space. The spatial tuning of these neurons emerges gradually in an experience-dependent manner after the onset of hearing, but the relative contributions of peripheral and central factors in this process of maturation are unknown. We have studied the postnatal development of the projection to the ferret SC from the nucleus of the brachium of the inferior colliculus (nBIC), its main source of auditory input, to determine whether the emergence of auditory map topography can be attributed to anatomical rewiring of this projection. The pattern of retrograde labeling produced by injections of fluorescent microspheres in the SC on postnatal day (P) 0 and just after the age of hearing onset (P29), showed that the nBIC-SC projection is topographically organized in the rostrocaudal axis, along which sound azimuth is represented, from birth. Injections of biotinylated dextran amine-fluorescein into the nBIC at different ages (P30, 60, and 90) labeled axons with numerous terminals and en passant boutons throughout the deeper layers of the SC. This labeling covered the entire mediolateral extent of the SC, but, in keeping with the pattern of retrograde labeling following microsphere injections in the SC, was more restricted rostrocaudally. No systematic changes were observed with age. The stability of the nBIC-SC projection over this period suggests that developmental changes in auditory spatial tuning involve other processes, rather than a gross refinement of the projection from the nBIC.  相似文献   

20.
A retrograde neuronal tracer (Fast Blue) was injected in the cervical end of the uterine horn of virgin rats. The majority of the retrogradely labeled post-ganglionic sympathetic neurons were found in the sympathetic chain (74%). The superior mesenteric ganglia, inferior mesenteric ganglia and suprarenal ganglia accounted for 22, 3 and <1%, respectively. The distribution of neurons in the sympathetic chain labeled from the uterus resembles that described for other pelvic organs.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号