[SOLVED] How to fix the error "argument "modelName" is missing, with no default" when using MVN package

How to fix the error "argument "modelName" is missing, with no default" when using MVN package

I am using the MVN package, in R, to find whether each class of the dataset iris is multivariate normal or not. I used the below code earlier in the day and generated results from it. However, I went to revisit it and now keep getting the following error message:

Error in mvn(data = iris[Species == m[1], 1:4], mvnTest = c("mardia")) : 
  argument "modelName" is missing, with no default

Can not figure out what this means and how to fix it !

Code:

#Mardia's Test
SM<-mvn(data=iris,subset="Species", mvnTest="mardia")

SM$multivariateNormality

SetosaPlot<-mvn(data=iris, subset="Species", multivariatePlot="qq")

Solution

You loaded the mclust package. When you did so you should have seen a warning

The following object is masked from ‘package:MVN’: mvn

So now mvn() is calling mclust::mvn() (i.e. the mvn function in the mclust package) rather than MVN::mvn().

In general you can make sure you get the version from the MVN package by using

MVN::mvn(data=iris, subset="Species", multivariatePlot="qq")

If you want to know where R is finding mvn, try find("mvn")
In general, to resolve these kinds of problems you should start a clean R session, so that you know you're starting with no packages loaded.

(By the way, no real data set is ever truly multivariate normal; you're not testing "whether it is MVN or not", but rather whether it is close enough to MVN that you can't reject the null hypothesis of multivariate normality ...)