医学科研或论文中常见的统计学问题

医学统计学在医学科研中占有重要地位,统计方法正确使用与否直接影响论文的结果和质量,但是具体使用过程中统计学方法或指标常常被混淆或使用不妥.本文就科研设计、数据描述、推演结论等方面容易混淆的统计学常见问题进行简要阐述,并举例分析可能出现误用的指标和方法,提高医务工作者对医学统计学的认识.     

医学科研中的移植方法

医学科研中的移植方法广东医学院马列主义教研室（湛江５２４０２３）张飞燕一、医学研究中移植方法的类型１．以概念或理论为移植体的移植方法在医学研究中,人们常常借助于其它学科的某些概念或理论,导致了医学上重大的理论突破或新的医学治疗方法的产生。早在１６１５...     

浅谈医学科研思维的逻辑性

医学科研思维过程中最重要的就是医学假说的提出、验证,推理和遵守逻辑思维的过程。它以抽象的概念、判断、推理为思维形式,通过分析、综合、比较、分类等多种逻辑思维方法进行操作,以达到它的最终目的。逻辑思维能力对于医学科研工作者是至关重要的,医学科研工作者应该不断加强逻辑修养,不断提升科研思维水准。     

难题、辩护与原则的确定--对"安慰剂对照双盲法人体实验"的医学伦理思考

从技术要求上看 ,针对人的药物或其他治疗方法的人体实验 (即涉及人体的医学实验 )研究 ,往往采取“对照”的方法和原则进行 ,而在各种对照中 ,对受试者通过随机分组、使用安慰剂和利用双盲法的“安慰剂对照双盲法人体实验”是其中常规的技术要求和做法 ,这种做法是为了保证科研结论的客观性和增强人们对科研结论的可信度。但必须十分清醒地认识到其中存在大量医学伦理难题 ,需要对此进行伦理学辩护 ,并确定解决难题的伦理学原则。1　伦理难题的存在◆“安慰剂对照双盲法人体实验”是获取研究结论的惟一手段选择吗 ?可以适应于所有的实验吗 …     

医学科研与医学科研伦理的辩证思考

医学科研中出现许多伦理问题。其必然性在于科学与伦理的不同：即属性不同、评价标准不同、变革速度不同。医学伦理可以告诉人们什么样的医学科研活动是善的,什么样的科研行为是应该做的。医学科研中要把握医学伦理观,体现医学科技观,富有医学创新观。     

纠正医学科研价值取向的扭曲

正近年来,国家对医学科研的投入不断加大,我国在国际有影响力的期刊上发表的论文快速增多,青蒿素的研究成果获诺贝尔生理学或医学奖,我国医学科研水平有了显著提升。但总体看,我国医学研究水平仍处于大而不强的状况,论文虽越来越多,真正转化为有实效的成果甚少。医学科研中存在的最突出问题是为什么做研究?为了生存、功利而研究是我国当下普遍存在的医学科研价值扭曲的体现:没有博士学位就不可能在大城市、大     

2012年诺贝尔生理学或医学奖对培养医学研究生科研思维的启示

约翰·格登和山中伸弥因在细胞核重编程研究领域的杰出贡献,获得2012年诺贝尔生理学或医学奖.介绍了科学研究的历程,探讨诺贝尔生理学或医学奖对培养医学研究生科研思维的有益启示.从培养敢于突破、科技创新精神、逆向思维能力、实事求是的科学态度和遵守学术道德、尊重医学伦理等方面加强研究生教育.塑造求真务实,坚韧不拔的科研素质,善于运用逆向思维,重视借鉴前人研究成果,鼓励尽早参与科研活动,培养研究生的科研思维,提高研究生的科研能力.     

三大中华杂志重视临床科研及论文质量15年回顾

１９８０年１０月中华医学杂志编委会召开医学科研设计座谈会,次年发表《纪要》,系我国医学科研史上一重要文献。１５年来,该刊与中华内、外科杂志重视医学科研与论文质量,发表约２０万字近百篇论文,大致分为１９８０—１９８１年三刊启动期,１９８２—１９８４年统计学指导期,１９８５—１９８９年刊评讲座活跃期,１９９０—１９９４年科研方法继教期,各期有里程碑式大事要文突出于中,影响深远,业绩卓著。对存在的问题及其展望是：在提高杂志质量方面,各杂志宜联合协力;质量教育要面对基层广大医护人员;进一步做好刊评书评;统一投稿要求,参与国际期刊交流等。     

食管癌诊断方法研究进展及面临的问题

食管癌诊断方法研究,涵盖流行病学、生物化学、病理学、肿瘤学、分子生物学等多学科。临床需求是医学科学进步的原动力,科技进步推动了医学发展,食管癌诊断方法的研究和正确的科研思路在控制食管癌发病率和死亡率中起重要作用。     

医务人员对医学科研伦理的认知及培训情况调查

调查某三甲医院医务人员对医学科研伦理的认知及培训情况。选取该院300名医务人员作为研究对象,了解其对医学伦理委员会的认知情况以及教育培训情况。结果显示,医务人员对医院设置医学伦理委员会、科研需通过委员会审核的认知及工作期间参加医学伦理学培训的占比分别为48.33%、39.33%和54.00%;医生对医学伦理委员会的知晓情况优于技师和护士,硕士及以上学历的医务人员对医学伦理委员会的知晓情况优于大专及以下学历,差异均有统计学意义(P0.05)。医务人员对医学伦理学的认识不足,工作期间接受的培训也较少,医院应重视医学伦理学的建设工作。     

A consideration of the validity and reliability of suicide mortality data

The question of the validity and reliability of suicide statistics may be considered at three levels: (1) Are suicide deaths misidentified or differentially identified across jurisdictions or over time? (2) To what degree are suicide deaths misidentified? and (3) Is the degree to which suicides are misidentified sufficient to threaten the validity of research based on suicide statistics? There is general agreement that suicides are likely to be undercounted, both for structural reasons (the burden-of-proof issue, the requirement that the coroner or medical examiner suspect the possibility of suicide) and for sociocultural reasons. There is also substantial anecdotal and empirical evidence suggesting that the mode of death for some true suicides is in fact certified as other than suicide. Overall, it does not seem that very many true nonsuicides are incorrectly certified as suicides. There is not, however, much agreement as to the degree to which true suicides are undercounted. At least some of the inconsistencies in the findings of different investigators arise because the validity of suicide certification seems to vary from place to place. But the source of apparent conflicts in many of the findings is undoubtedly the lack of a "gold standard" against which the verdicts of any given death certification process can be measured. At best, we can estimate that the sensitivity with which coroners and medical examiners certify true suicides varies from approximately 55% to 99%. A central question in estimating the sensitivity of suicide certification is this: What proportion of true suicides are either equivocal or likely to go unsuspected by the coroner or medical examiner? Very little has been done to investigate this issue. Yet the sensitivity of suicide certification clearly varies for equivocal versus unequivocal suicides. As shown in Table 1.2, specificity is also at issue when it comes to certifying equivocal cases. The final question--whether the degree of undercounting of suicide deaths is so great that it threatens the validity of research based on official statistics--is at the crux of the general concern about suicide certification. There are examples of studies in which conclusions based on crude comparisons of reported suicide statistics appear to be invalid. For the most part, these are comparisons among nations with substantially differing death certification procedures. When official statistics are interpreted with a degree of caution and an understanding of the source and direction of biases likely to affect the published rates, however, it seems unlikely that major conclusions based on these statistics will be in error.(ABSTRACT TRUNCATED AT 400 WORDS)     

CONFUSED THOUGHT AND MODES OF PRESENTATION

Ruth Millikan has long argued that the phenomenon of confused thought requires us to abandon certain traditional programmes for mental semantics. On the one hand she argues that confused thought involves confused concepts, and on the other that Fregean senses, or modes of presentation, cannot be useful in theorizing about minds capable of confused thinking. I argue that while we might accept that concepts can be confused, we have no reason to abandon modes of presentation. Making sense of confused thought requires recognizing modes of presentation.     

A planar and a volumetric test for stereoanomaly

Stereoanomaly is the failure to see differences in depth when the viewer is presented with stimuli having different magnitudes of stereoscopic disparity. In the absence of eye movements, everyone suffers from stereoanomaly for extremely large disparities. Typically, such disparities are seen at the same depth as monocular stimuli. However, about 30%, of the population exhibit some form of stereoanomaly even for very small disparities, provided eye movements are avoided. In some cases, the sign of the disparity will be confused, and the perceived depth will be incorrectly seen as 'behind' rather than 'in front of' the fixation point, for example. Because anomalies provide useful information about perceptual mechanisms, tests that measure and quantify the extent of a blindness are important investigative tools for research. Here we offer two easy-to-administer tests for stereoanomaly. The first test is based on depth judgments of two bars relative to a fixation point. The second test involves judgments of volumetric stimuli, seen stereoscopically. In each case, subjects indicate depth by setting a rectangle (with fixed base) to match the perceived depth. Although both tests are correlated, some differences in stereo processing are seen, depending upon whether or not the stimuli are presented near the point of fixation.     

Is meaning implicated in illusory conjunctions?

According to feature-integration theory, when attention is diverted from a display, features from different objects in that display may be wrongly recombined, giving rise to "illusory conjunctions" (Treisman & Schmidt, 1982). Two experiments are reported that examine the nature of these illusory conjunctions. In displays that contain color names and adjectives printed in colored ink, subjects made two kinds of interesting and previously unreported errors. Consider, for example, a display that included the word BROWN in red ink and the word HEAVY in green ink. Subjects would sometimes incorrectly report that the word RED or the ink color brown had appeared in the display (e.g., RED in green ink or HEAVY in brown ink). It appears that subjects extract semantic representations from input and are sometimes confused about whether a particular representation has been extracted from a word or a color patch. Contrary to feature-integration theory, these findings suggest that illusory conjunctions may occur with high-level codes as well as with perceptual features.     

认知诊断测验中基于信息矩阵的多群组DIF检验

基于改进的Wald统计量,将适用于两群组的DIF检测方法拓展至多群组的项目功能差异（DIF）检验;改进的Wald统计量将分别通过计算观察信息矩阵（Obs）和经验交叉相乘信息矩阵（XPD）而得到。模拟研究探讨了此二者与传统计算方法在多个群组下的DIF检验情况,结果表明：（1）Obs和XPD的一类错误率明显低于传统方法,DINA模型估计下Obs和XPD的一类错误率接近理论水平;（2）样本量和DIF量较大时,Obs和XPD具有与传统Wald统计量大体相同的统计检验力。     

Randomization tests as alternative analysis methods for behavior‐analytic data

Randomization statistics offer alternatives to many of the statistical methods commonly used in behavior analysis and the psychological sciences, more generally. These methods are more flexible than conventional parametric and nonparametric statistical techniques in that they make no assumptions about the underlying distribution of outcome variables, are relatively robust when applied to small‐n data sets, and are generally applicable to between‐groups, within‐subjects, mixed, and single‐case research designs. In the present article, we first will provide a historical overview of randomization methods. Next, we will discuss the properties of randomization statistics that may make them particularly well suited for analysis of behavior‐analytic data. We will introduce readers to the major assumptions that undergird randomization methods, as well as some practical and computational considerations for their application. Finally, we will demonstrate how randomization statistics may be calculated for mixed and single‐case research designs. Throughout, we will direct readers toward resources that they may find useful in developing randomization tests for their own data.     

The (mis)reporting of statistical results in psychology journals

In order to study the prevalence, nature (direction), and causes of reporting errors in psychology, we checked the consistency of reported test statistics, degrees of freedom, and p values in a random sample of high- and low-impact psychology journals. In a second study, we established the generality of reporting errors in a random sample of recent psychological articles. Our results, on the basis of 281 articles, indicate that around 18% of statistical results in the psychological literature are incorrectly reported. Inconsistencies were more common in low-impact journals than in high-impact journals. Moreover, around 15% of the articles contained at least one statistical conclusion that proved, upon recalculation, to be incorrect; that is, recalculation rendered the previously significant result insignificant, or vice versa. These errors were often in line with researchers’ expectations. We classified the most common errors and contacted authors to shed light on the origins of the errors.     

Neural correlates of feigned memory impairment are distinguishable from answering randomly and answering incorrectly: an fMRI and behavioral study

Previous functional magnetic resonance imaging (fMRI) studies have identified activation in the prefrontal-parietal-sub-cortical circuit during feigned memory impairment when comparing with truthful telling. Here, we used fMRI to determine whether neural activity can differentiate between answering correctly, answering randomly, answering incorrectly, and feigned memory impairment. In this study, 12 healthy subjects underwent block-design fMRI while they performed digit task of forced-choice format under four conditions: answering correctly, answering randomly, answering incorrectly, and simulated feigned memory impairment. There were three main results. First, six areas, including the left prefrontal cortex, the left superior temporal lobe, the right postcentral gyrus, the right superior parietal cortex, the right superior occipital cortex, and the right putamen, were significantly modulated by condition type. Second, for some areas, including the right superior parietal cortex, the right postcentral gyrus, the right superior occipital cortex, and the right putamen, brain activity was significantly greater in feigned memory impairment than answering randomly. Third, for the areas including the left prefrontal cortex and the right putamen, brain activity was significantly greater in feigned memory impairment than answering incorrectly. In contrast, for the left superior temporal lobe, brain activity was significantly greater in answering incorrectly than feigned memory impairment. The results suggest that neural correlates of feigned memory impairment are distinguishable from answering randomly and answering incorrectly in healthy subjects.     

Segmentation of the speech stream in a non-human primate: statistical learning in cotton-top tamarins

Previous work has shown that human adults, children, and infants can rapidly compute sequential statistics from a stream of speech and then use these statistics to determine which syllable sequences form potential words. In the present paper we ask whether this ability reflects a mechanism unique to humans, or might be used by other species as well, to acquire serially organized patterns. In a series of four experimental conditions, we exposed a New World monkey, the cotton-top tamarin (Saguinus oedipus), to the same speech streams used by Saffran, Aslin, and Newport (Science 274 (1996) 1926) with human infants, and then tested their learning using similar methods to those used with infants. Like humans, tamarins showed clear evidence of discriminating between sequences of syllables that differed only in the frequency or probability with which they occurred in the input streams. These results suggest that both humans and non-human primates possess mechanisms capable of computing these particular aspects of serial order. Future work must now show where humans' (adults and infants) and non-human primates' abilities in these tasks diverge.     

Detection and validation of unscalable item score patterns using item response theory: an illustration with Harter's Self-Perception Profile for Children

We illustrate the usefulness of person-fit methodology for personality assessment. For this purpose, we use person-fit methods from item response theory. First, we give a nontechnical introduction to existing person-fit statistics. Second, we analyze data from Harter's (1985) Self-Perception Profile for Children (Harter, 1985) in a sample of children ranging from 8 to 12 years of age (N = 611) and argue that for some children, the scale scores should be interpreted with care and caution. Combined information from person-fit indexes and from observation, interviews, and self-concept theory showed that similar score profiles may have a different interpretation. For some children in the sample, item scores did not adequately reflect their trait level. Based on teacher interviews, this was found to be due most likely to a less developed self-concept and/or problems understanding the meaning of the questions. We recommend investigating the scalability of score patterns when using self-report inventories to help the researcher interpret respondents' behavior correctly.