rntransform {GenABEL} | R Documentation |
Rank-transformation to normality of a variable or residuals from GLM analysis.
rntransform(formula,data,family=gaussian)
formula |
GLM formula for the variable to be transformed, or just the variable |
data |
data.frame or gwaa.data object containing the data |
family |
GLM family |
Rank-transformation to normality generates perfectly normal distribution from ANY distribution, unless many/heavy ties are present in variable (or residuals, if formula is used).
When formula is supplied, this procedure first calls ztransform
,
and then applies rank transformation to residuals.
Vector containing transformed variable, distributed as standard normal.
Yurii Aulchenko
# uniformly distributed variable x <- round(runif(200)*100) # get 7 missing values x[round(runif(7,min=1,max=100))] <- NA # Z-transform y0 <- ztransform(x) # Rank-transform to normality y1 <- rntransform(x) # test normality of the original and transformed var shapiro.test(x) shapiro.test(y0) shapiro.test(y1) # plot histogram par(mfcol=c(3,1)) hist(x) hist(y0) hist(y1)