流行病学研究方法总结分析

1、1. 于研究对象参与研究的过程中可能会怎样做，提高统计学功效高A run-in period in a randomized clinical trial (RCT) can be defined as a specified period time after enrollment and prior to1. 于研究对象参与研究的过程中可能会怎样做，提高统计学功效高A run-in period in a randomized clinical trial (RCT) can be defined as a specified period time after enrollment an

2、d prior to participantseligibility and commitmenttoa studyt is allotted to further easure 2.GIS地理信息系GIS真正的功能在于它利用空间分析技术对空间数据的分析将空间分析应用于流行病学研究, 的、疗资源进行有效的配置。然而, 从整体上看, 空间分析在流行病学研究中的应用完善之处, 并且长期以来积累的流行病学数据缺乏空间属性, 这些都限制了空间GIS在疾病控制和流行病学中的应用包括：疫病流行专题地图的绘制3.Zelens“randomising patients before consent to pa

3、rticipate has been sought”. Two types of design exist: double and single he double consent patients are initially the treatment to which they were randomised; however, if they decline the randomised they can then be offered alternative including the experimental he consent only patients offered the

4、experimental treatment are told there treatment (the control) available. Patients randomised to the control treatment are not allowed experimental treatment (although they are given unhindered s to any usual ysisisundertakenwithpatientsretainingtheiroriginalThere are obvious ethical problems in usin

5、g Zelens design to randomise patients their consent8(though treatment consent is always sought). For erventions,however,as screening, this may be the only practical design. For le, if all he cancer screening trials had been screened but only a random half had been there would have as screening, this

6、 may be the only practical design. For le, if all he cancer screening trials had been screened but only a random half had been there would have been an ethical dilemma of not offering further investigation and treatment controlpatientswhoappeared tobeathigh Zelensdesigncanhaveotherdisadvantages.Ifth

7、etrialrusiveollectionmonitoringthenZelensdesignascontrolpatientswillbeawareofthestudy.tdollectionisnotfeasible,itmaynotsibletouserestrictiveinclusiveorpatientrecruitmentcriteria.Furthermore,ifmanypatientsrefusetheiroriginaltreatment,thisleadtoareductionin er.Boththesefactorswillleadtotheneedforalarg

8、ele 4.SusceptibilityBiases（易感性偏倚different ervention es.Ifdifferentstudygroupshaveprognostic unequallyincrease/decreaseriskto1group,making1groupsceptibleto,and/orundesirableeffectsfromervention,astudysceptibilityInsummary,susceptibilitybiasescanbecreatedbyselectioncriteria,bychanneling,orotherconfoun

9、dingfactorsaswellasbyvariousfeaturesofaninappropriateroup.thesourceofbias,theprognostict e,isidentifiableand abletomeasuredinallgroups,aswithsomeselectioncriteria,itcansometimesbecontrolledforstratificationorysistechniques.Thisismostfeasiblewhenconcurrentgroups compared.Onlyrandomizationcontrolsforu

10、nidentifiableprognostictmight ernalbias.Butrandomizationalonecannotcontrolforallexternaltmayaffect5.otherDetection bias occurs if the methods for e are not uniform either within a ornatestandaTransfer bias occurs when a study feature ervention groups to have unequal follow-easurestheeffectivenessofoneerventionrelativeto anotherby 2009 因任课老师出国开会原课2009 因任课老师出国开会原课程安排中 2009-4-1（周三研究方法选择与病因推断暂停将与 2009-4- 12009-02-22009-02-32009-02-42009-02-52009-03-62009-03-7