Performing a CFA with 'count' data in lavaan

[Olivia]

Dear all, 

I have searched for previous answers to this question, but the most recent I can find are from 2015 and might be out of date!

I am performing a confirmatory factor analysis. There are five endogenous variables in total, three are categorical data and two are count data. By count data, I mean the number of occurrences of a certain event/number of a certain object (e.g. number of tumours on MRI scan). I have declared the categorical data as 'ordered' using the ordered function in my data.frame, but am not sure how to treat the count data? Can anyone advise me as to whether it's possible to run a CFA in lavaan using count data? And if so, how should I specify my count variables?

Many thanks in advance,

Olivia

[Terrence Jorgensen]

Can anyone advise me as to whether it's possible to run a CFA in lavaan using count data? And if so, how should I specify my count variables?

lavaan does not have link functions for count data. Mplus has options for Poisson, negative binomial, and zero-inflated Poisson.  

Poisson variables with mean > 10 are approximately normally distributed.  If your counts have high means and sufficient variability to be approximately continuous (e.g., unimodal histogram, at least 5-7 unique response categories), I think you can treat them as continuous.

Terrence D. Jorgensen

Postdoctoral Researcher, Methods and Statistics

Research Institute for Child Development and Education, the University of Amsterdam

UvA web page: http://www.uva.nl/profile/t.d.jorgensen

[Olivia]

Hi Terrence, 

Thanks for getting back to me. I thought that was the case, but it's good to have it confirmed. Unfortunately my data have a mean < 10, so I'll have to check out MPlus!

Thanks again,

Olivia

[Elisa Altgassen]

Hi Terrence, 

Just wanted to ask, whether there is any update in lavaan that allows for modeling count data today (as this thread is 8 years old). 

Thank you very much in advance for a quick reply, 

Best,
Elisa