# [R] mardia's test

From: Jiao Yang <yj316_at_gwu.edu>
Date: Sat, 16 Jun 2007 16:50:08 -0400

In the R code of Mardia's test, what does the line " x1 = x[x[, p] == i, -p]" mean? Thanks a lot!

function (x)
{

p = dim(x)
f = p - 1
clases = length(table(x[, p]))
for (i in 1:clases) {

x1 = x[x[, p] == i, -p]

```        ndat = dim(x1)
mo3 = mo3(x1)
mard1 = ndat * mo3/6
cat("Mardia's test for class", i, "\n")
cat("mard1=", mard1, "\n")
p1 = 1 - pchisq(mard1, df = f * (f + 1) * (f + 2)/6)
cat("pvalue for m3=", p1, "\n")
mo4 = mo4(x1)
mard2 = (mo4 - f * (f + 2))/sqrt(8 * f * (f + 2)/ndat)
cat("mard2=", mard2, "\n")
p2 = 2 * (1 - pnorm(abs(mard2)))
cat("p-value for m4=", p2, "\n")
if (p1 < 0.05 || p2 < 0.05)
cat("There is not statistical evidence for normality in class",
i, "\n")
else cat("There is statistical evidence for normality",
"\n")
```

}
}

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