CROISEMENT DE DEUX VARIABLES QUALITATIVES

cramer <- function(x,y) {
    res <- chisq.test(x,y, correct=FALSE)
    chi2 <- as.numeric(res$statistic)
    n <- length(x)
    p <- length(levels(x)) 
    q <- length(levels(y))
    m <- min(p-1,q-1)
    V <- sqrt( chi2 / (n*m) )
    return(V)
}

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CROISEMENT D'UNE VARIABLE QUALITATIVE ET D'UNE VARIABLE QUANTITATIVE

vartot <- function(x) {res <- sum((x-mean(x))^2) ; return(res)}

varinter <- function(x,gpe) {
    moyennes <- tapply(x,gpe,mean)
    effectifs <- tapply(x,gpe,length)
    res <- (sum(effectifs*(moyennes-mean(x))^2))
    return(res)
    }

eta2 <- function(x,gpe) {res <- varinter(x,gpe)/vartot(x) ; return(res)}

graphnf <- function(x,gpe) {
    stripchart(x~gpe)
    points(tapply(x,gpe,mean),1:length(levels(gpe)),col="red",pch=19,cex=1.5)
    abline(v=mean(x),lty=2)
    moyennes <- tapply(x,gpe,mean)
    traitnf <- function(n) segments(moyennes[n],n,mean(x),n,col="blue",lwd=2)
    sapply(1:length(levels(gpe)),traitnf)
    }