医学统计学英文CH01-introdu课件.ppt

1、Postgraduate books recommended by Degree Management and Postgraduate Education Bureau,Ministry of EducationMedical Statistics(the 2nd edition)医学统计学英文CH01 introduArrangement:total 72 class hours,two classes each week医学统计学英文CH01 introdu chapter 1 Introduction1.Key definitions2.the steps for medical st

2、atistics3.Brief history of Statistics医学统计学英文CH01 introduStatisticsnThe science for data collection,sorting,and analysis.医学统计学英文CH01 introdu Definition：the science that study the collection,sorting and analysis of medical data.Characteristics：1、Using the quantity to reflect the quality 2、Using chance

3、 events(uncertainty)to reflect the inevitability(rules)Medical Statistics医学统计学英文CH01 introduLearning objectives：1、Basic principles and methods of Statistics （Learning Emphasis）2、Application Statistics(Clinical Medicine,Preventive Medicine,and Health Care Management)Medical Statistics医学统计学英文CH01 intr

4、oduPurpose：a tool for medical researchEmphasis:statistical indicators used for calculating or comparing the quantitative characteristics of populationExample:health expectation infant mortalityMedical Statistics医学统计学英文CH01 introduSection 1.Key definitions医学统计学英文CH01 introdu variable,individual,sampl

5、e and population医学统计学英文CH01 introdu individual（observatory unit）：the basic unit in statistical research,it depends on the purpose.variable（indicator）：individual characteristics examples:height、weight、gender、blood type、treatment effect etc.医学统计学英文CH01 introduVariable value：the value of variablesExamp

6、les:height 1.65 meters weight 52 kggender female blood type “O”laboratory test negative treatment effect betterData:composed of a lot of variable values.Example:Data for blood glucose医学统计学英文CH01 introdu homogeneity：common characteristics for the given individuals example：the heights of the boys with

7、 the age of 7 living in Changsha 2004 variation:difference existing among the variable values of homogeneity individuals example:the different heights of the boys with the age of 7 living in Changsha 2004 医学统计学英文CH01 introdu Definition：the whole homogeneity individuals determined by specific purpose

8、.example：all the heights of boys at 7 that lived in Changsha 2004 finite population：the space,time and population for a specific population have been limited.infinite population：no time and space limits for the population.Such populations only exist in imagination,so it is called infinite population

9、.population医学统计学英文CH01 introdudefinition：the set of variable values of some individuals sampled from the population at random.Example:the heights of 200 boys at 7 from Changsha.sample医学统计学英文CH01 introduSampling studySample information(statistic)Population characteristics（parameter）inferencenote：samp

10、ling is only the way to get information,inferring the population is our purpose医学统计学英文CH01 introdu、variable and data 医学统计学英文CH01 introdu measurement data:it is also called as quantitative or numerical data.Its value is quantitative.Measurement data always has measurement units.example：height data,we

11、ight data医学统计学英文CH01 introdu enumeration data:qualitative or count data.For such data,it needs to classify the observation units before and count them.Its value appear different characteristics and sorts.Binomial:gender,live or death,yes or no.Multiple：blood type,A、B、O、AB.医学统计学英文CH01 introdu ranked

12、data:ordinal or semi-quantitative data.It need to classify observatory units into different classes according the extent before calculate the frequencies of each groups.There exists obvious differences among different classes.example:to evaluate the treatment effect of one drug on heart failure,we u

13、se the indicator(cured,better,worsen,dead)to assess the treatment effect.Choosing of statistical methods depends on the data type to a great extent。医学统计学英文CH01 introduData transformationQuantitative data ranked data（multiple）binomial data医学统计学英文CH01 introduexample：WBC（1/m3）count of five persons：3000

14、 6000 5000 8000 12000 quantitative variablelower normal normal normal higher qualitative variable Binomial data:normal 3 persons;abnormal 2 personsMultiple category data:lower 1 person;normal;3 persons;higher 1 person医学统计学英文CH01 introdu error医学统计学英文CH01 introdudefinition：the difference between measu

15、rement value and true value.1、rand error：unstable and changing at random errors that caused by uncontrolled factors.Commonly,rand errors are referred to those errors appearing during repeated measurements and sampling.Often,measurement error is extremely lower than sampling error.In Statistics,sampl

16、ing error is the main study contents.医学统计学英文CH01 introdu2.Nonrandom error is divided into systematic error and non systematic error:Systematic error:it is produced in experiment and keeps constant or changes according certain rules.Usually,its reasons are known and controllable.Nonsystematic error（g

17、ross error）:it is always caused by obvious grosses.医学统计学英文CH01 introdu、frequency and probability医学统计学英文CH01 introdu 1Frequency Given the same condition,repeat a trial for n times independently.Among n trials,A appears for m times，so the ratio of m/n is called the frequency of random event A among n

18、trials.(A)Pm n医学统计学英文CH01 introdu 2probability:the likelihood of random events.Given the same condition,repeat a trial for n times independently.Among n trials,A appears for times，so the ratio of is called the frequency of random event A.As n increases gradually,the frequency will approach a constan

19、t.The constant is called the probability of random event A and expressed in .In common,it is abbreviated as ./fnf(A)PP/fn医学统计学英文CH01 introdu=1 A is absolute event.=0 A is absolutely nonoccurrence event1 A is random event.PPPif（A），nonrandom event;if（A），if 0（A），Range：1P0（A）医学统计学英文CH01 introdu Frequenc

20、y is used to describe the sample,while the probability for the population.m/n is the estimation of .As trials increases,the estimation value is more reliable.(A)P医学统计学英文CH01 introdu small probability event:Because the conclusions are made based on a certain significance level,statisticians always se

21、lect as judge criterion.So such events with are called small probability events.It means that such events happen rarely and can be regarded as nonoccurrence.(A)0.05(A)0.01PP或(A)0.05(A)0.01PP或医学统计学英文CH01 introduSection 2 the steps for statistical work医学统计学英文CH01 introduHere,it means statistical desig

22、n,the most important factor for a successful research.It involves the arrangements for the process of data collection,sorting and analysis.design 医学统计学英文CH01 introdu 3controlThree principles for experiment design1randomization2.Replication 医学统计学英文CH01 introduobjective：to gather accurate and reliable

23、 raw data data sources：statistical reporting routine records purposive surveys or experiments statistical yearbook and special data bookrequirements：1、randomization 2、sufficient sample size Data collection医学统计学英文CH01 introduData sortingIt is the process that cleans and systematizes raw data.Data sor

24、ting prepares the required data for next step,data analysis.医学统计学英文CH01 introdu Data/statistical analysis objective：to illustrate the rules hidden in the data.It includes two aspects:1.statistical description：it is the process of describing the characteristics of data using statistical indicators,st

25、atistical charts and statistical tables.2.statistical inference：the process of using sample statistic to infer population parameter.It consists of:parameter estimation and hypothesis testing.医学统计学英文CH01 introduStatistical descriptionStatistical inferenceindicatorTable and chartParameter estimationHypothesis testingStatisticalanalysis医学统计学英文CH01 introdu医学统计学英文CH01 introdu