[R] Help with factanal and missing values

[John Fox]

Dear Antonio, 

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of 
> Antonio Prioglio
> Sent: Tuesday, July 13, 2004 9:32 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Help with factanal and missing values
> 
> Hi list,
> 
> I'm performing a series of confirmatory factor analysis on 
> different groupings of items from data collected with 
> questionnaires. There are some missing values.
> 
> For those sets with no missing values I call
> factanal(datamatrix,factors=n)
> 
> where datamatrix is a table of all observations for the items 
> under investigation.
> 
> This call fails when there are missing values.
> help(factanal) does not give an example on calls with  
> na.action and and mentiones a formula.
> 
> (Venables and Ripley, 2002 give only one example on p. 323 
> for a case where the covariance has already been calculated)
> 
> Could someone give me an example on such a call for a simple CFA?

Two solutions are to use na.omit() to eliminate observations with missing
data -- factanal(na.omit(datamatrix), factors=n) -- or to use a formula
argument to factanal and pass the data as a data frame via the data argument
-- factanal(~ var1 + ... + vark, factors=n, data=as.data.frame(datamatrix)).

By the way, what factanal() does would conventionally be described as
exploratory, not confirmatory, factor analysis. For the latter, you might
try the sem package.

I hope that this helps,
 John