n种统计方法的应用条件

一parameter test

numerical data

1.Z:independence,normality,homogeneity

used in variance of population is known,or sample size is large(n＞50,n1+n2＞60)

2.t:independence,normality,homogeneity(INH)

used in variance of population is unknown,or sample sizw is small

one sample

two independent sample

paired sample

(df=n-1)

3.ANOV A(F test):INH

used in comparison of more than two means of groups.

pletely randomized design(df of error =N-g)

b.randomized block design(df of error=(g-1)(k-1))

tin square design

(b and c can control confounding factors)

further:want to know which pairwise groups have significant difference

a.SNKq unplaned comparison

b.Dunnett t:planed comparison

c.LSDt:compare choosen two groups

categorical data

chi square test:usd in

a.how closely an observed distribution matches expected distribution(goodness of fit)

b.whether two variables are independent

c.whether the difference of proportion is significant

1.fourfold table df=1

n≥40,E≥5:pearson chi square test

1≤E＜5:Yate's continuity correction

n＜40:fisher's exact test

2.paired fourfold table

b＋c＜40:continuity correction

used in:to same objects,different methods

3.R*C table :df=(r-1)(c-1)

cell numbers of E＜5 more than 1/5,use fisher's exact test

phi coefficient ,cramer's V,contigency coefficient are the measures of association for two categorical variables

二.non parameter test

1.wilcoxon signed rank test :used in paired sample and one sample ,when they do not satisfy the condition of parameter test.(statistics:T-,T+任选)

当n大于50无法查表时，T~N(n(n+1)/4,n(n+1)(2n+1)/24)

且当n不足够大时，需要continuity correction

当秩次重复超过1/5时，Zc

2.wilcoxon test for two independent sample:混合编秩，分别求和(T1,T2,选n较小者的T)

3.rank sum test for ordinal data.对于单向有序，选用行列表检验时无法得出疗效差别时

4.K-W test for :the number of groups more than two(statistics:H)

三.regression

1.simple linear regression :used in analysis of the influence of explanatory variable(independent variable) to the outcome variable(dependent variable)

a.X,Y are numerical data

b.X,Y have linear relationship

c.Y are nomal distribution for each given X

d.observations are independence

e.equal variance

(line)

几个概念:

linear regression model

coefficience of determinationR^2

residual

residual standard deviation

residual plot(residual analysis)

2.multiple linear regression:对Y的条件和simple linear regression一样，X可以是numerical data,binary data,ordinal data

几个概念:

opimum subset regression

stepwise regression

adjust R^2

dummy variable

3.logistic regression:Y is binary data,X is numerical,binary,ordinal ed to find the etiology of diseases,because the coefficient of logistic regression β has relationship with OR 概念:

maximum likelihood function

四correlation

1.linear correlation:pearson correlation analysis

要求XY服从双变量正态分布(binariate normal distribution X,Y,e~N),才能用tr进行假设检验估计总体相关系数(且tr=tb，df=n-2)

2.rank correlation:spearman correlation

XY不服从双变量正太分布时

3.association of two categorical variables

phi coefficient

cramer v

continuity coefficient