[R] Mardia's multivariate normality test

[Jiao Yang]

Dear all,

I got this error message 

> library(dprep)
> mardia(Savg)
Error in cov(data) : 'x' is empty


But with the same data, I got 
> library(mvnormtest)
> mshapiro.test(Savg)

        Shapiro-Wilk normality test

data:  Z 
W = 0.9411, p-value = 0.6739

What does the error message "Error in cov(data) : 'x' is empty" mean?  Thanks a lot!

Jiao