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1、1,描述性研究,Descriptive Study,哈尔滨医科大学流行病学教研室 Department of epidemiology ，Harbin Medical University,2,Methods of study,Observational,Experimental,Theoretical,Descriptive study,Analytic study,Clinical trial Field trial Community intervention,three types of basic methods,Case-control study Cohort study,Cro
2、ss-sectional study Ecological study,3,Epidemiology is the study of the distribution and determinants of disease frequency in human population. Epidemiology: Principles and Methods by Brian MacMahon 1996,4,?,The distribution of Disease considers,Who is getting disease?Where is disease occurring?When
3、is disease occurring?,5,Person,Place,Time,Cases,Descriptive Epidemiology,Who? Where? When?,6,Descriptive study is to subset collected data or some survey data, included the data from experiment, to groups by different places, different time or different population character and descriptive the frequ
4、ency of disease and health. Helps to build the relationship between risk factors and disease or health, offer etiological clues.,描述性研究通过描述疾病或健康状况的三间分布情况，找出某些因素与疾病或健康状况间的关系，提供病因线索。,7,目 录,现况研究的概述现况研究的设计与实施 研究实例 生态学研究,Introduction of cross-sectional study Design and implementation of cross-sectional st
5、udy A case study Ecological study,Outline,8,第一节 现况研究概述 Introduction of Cross-sectional Study,基本概念 目的与应用特点与类型,Basic conceptMechanism Purposes and applications Characteristics and categories,9,一、基本概念 Conception,又称横断面研究也称患病率研究时点或期间和特定范围内人群中的有关变量(因素)与疾病或健康状况的关系,Cross-sectional study or prevalence study
6、Describes the relationship between disease or health and variables (factors) in the population at a particular point of time or period,10,Time,11,Schematic diagram of Cross-sectional Study,12,掌握目标群体中疾病或健康状况的分布提供疾病病因研究的线索,二、目的与应用Mechanism Purposes and applications,Describes the distributing of diseas
7、e or health events within populationsTo provide etiological clues,13,This figure shows the infant death frequency (per 1000 live births) in different countries,14,确定高危人群 评价疾病监测、预防接种等防治措施效果,二、目的与应用Mechanism Purposes and applications,To identify high risk groups in the populationTo evaluate the effect
8、 of surveillance，vaccination and disease prevention and control,15,研究特点 开始时一般不设对照组 现况研究的特定时间 在确定因果联系时受到限制 对不会发生改变的暴露因素，可以提示因果联系,三、特点与类型 Characteristics and categories,Characteristics No control group Particular point of time Limit to ensure the causal relationship To prompt causal relationship for t
9、he exposures that wont be changed,16,研究类型 普查 抽样调查,三、特点与类型 Characteristics and categories,Category CensusSampling survey,17,The census of the lifetime alcohol drinking status in America population,明确调查目的和类型确定研究对象确定样本量和抽样方法资料的收集资料的整理与分析常见偏倚及其控制研究的优点与局限性,第二节 现况研究的设计与实施 Design and implementation of cros
10、s-sectional study,To make the purpose and category of study To select the objects To determine the sample size and sampling method To collect data To sort and analyze data Bias and control Advantage and limitation,19,一、明确调查目的和类型 To make the purpose and category of study,根据研究提出的问题，明确调查目的 根据具体研究目的确定是普
11、查还是抽样调查,To make the purpose by the proposal of the studyTo select the survey method reference to the aim, census or sampling survey.,20,二、确定研究对象 To select the objects,某个区域内的全体居民或其中一部分 某一时点上的流动人员 某些特殊群体,Entire or part of the population in a region Floating population at a particular point of time. Ce
12、rtain special groups of people,三、确定样本量和抽样方法 To determine the sample size and sampling method,确定样本量预期现患率 ( P )允许误差（d）显著性水平（）,To determine the sample sizeExpected prevalence( P )Allowable error（d）Significance level（）,22,计量资料样本大小估计公式 Formulas for Numerical data,计数资料样本大小估计公式 Formulas for Categorical dat
13、a,23,抽样方法 Sampling Method非随机抽样Non-random sampling 随机抽样Random sampling,非随机抽样 Non-random sampling,选择样本时，加入人主观因素，使总体中每个个体被抽取的机会是不均等的,Non-random samples are selected by any kind of procedure that does not give all cases in the population equal chances to fall into the sample.,25,随机抽样 Random sampling,总体中
14、每一个对象都有同等机会被选入作为研究对象,Every person in the target population has the same known (and non-zero) chance of being included in the survey,26,随机抽样 Random sampling,单纯随机抽样 系统抽样 整群抽样分层抽样多级抽样,Simple random samplingSystematic samplingClustering samplingStratified samplingMultistage sampling,方 法,Methods,27,单纯随机抽
15、样(简单随机抽样),最简单、最基本的抽样方法 从总体N个对象中，利用抽签或其他随机方法抽取n个 总体中每个对象被抽到的概率相等,Simple random sampling,Simplest and basic method To select number n subjects by drawing lot or by using a table of random number from population with N units Equal chance for each subject in the target population,28,图31 总体与样本示意图,Fig 31
16、Diagram of population and sample,29,系统抽样(机械抽样),将总体各个个体单位按某种标志排列、连续编号 根据总体数N和确定的样本数n，计算抽样距离（N/n）,Systemic sampling,Rank every units by a character construct and number them Define the size of the sample and calculate sampling interval (k = N/n),30,系统抽样(机械抽样),3. 用单纯随机方法在第一组中确定一个起始号 4. 从此起始点开始，每隔K（K=N/n）个单位抽取一个作为研究对象,Systemic sampling,3. Draw a random number ( k) for starting 4. Draw every k units from first unit,31,图32 系统抽样示意图,
