Lecture9 non parametric methods Xⅰ aojin yu Department of Epi. And Biostatistics School of public health, Southeast unIvers sity
1 Lecture9 nonparametric methods Xiaojin YU Department of Epi. And Biostatistics, School of public health，Southeast university
Review: Type of data qualitative data(categorical data (1)binary(dichotomous, binomial) (2)multinomial(polytomous) (3 ordinal quantitative data
Review: Type of data ▪ qualitative data (categorical data) (1) binary (dichotomous, binomial) (2) multinomial (polytomous) (3) ordinal ▪ quantitative data 2
Measures of central tendency- quantitative data Mean normal distribution Geometric mean: positively skew and data can be transferred into normal distribution by log scale Median used by all data in general is often used to abnormal data
Measures of central tendency- quantitative data ▪ Mean: Normal distribution ▪ Geometric mean: positively skew and data can be transferred into normal distribution by log scale. ▪ Median: used by all data, in general, is often used to abnormal data
Measures of Dispersion- quantitative data Range, Interquartile range Variance and standard deviation coefficient of variation
Measures of Dispersionquantitative data ▪ Range, ▪ Interquartile range , ▪ Variance and standard deviation , ▪ coefficient of variation 4
Compare means by t-test type conditions Single sample x,n,μo t-test s/√n Paired t-test d s, n /√n Two group t: x,, Si, n1, test Assumption (n1-1)s2+(n2-1) n normality (-1)+V-Dx(+ Equality of variance
Compare means by t-test Assumption: ▪ normality ▪ Equality of variance Single sample t-test type Paired t-test Two group ttest conditions ,S,n,μ0 ,Sd ,n , s1 ,n1 , , s2 ,n2 x d H0 μ=μ0 μd=0 t s n x t / − 0 = s n d t d / − 0 = ) 1 1 ( ( 1) ( 1) ( 1) ( 1) 1 2 1 2 2 2 2 2 1 1 1 2 n n n n n s n s x x t + − + − − + − − = ν n-1 n1+n2 -2 np -1 1 x 2 x