[16] As a senior author, Formann also showed that the common assumption that the EM estimation of the two-parameter logistic model is not influenced by initial values is incorrect.

A revised version of this language-free intelligence test that has been calibrated against large contemporary samples of men and women is forthcoming.

[18] For his first habilitation (in psychology), Formann published a comprehensive monograph on latent class analysis[19] which continues to be widely cited for its clarity, depth, and originality, and hence is considered a true modern classic on this topic.

He introduced a novel method that allows estimating the proportion of studies missing in meta-analysis due to publication bias based on the truncated normal distribution.

[25] Formann provided both theoretical and empirical evidence that the application of the parallel analysis for uncovering the factorial structure of binary variables is not appropriate.

Results of a simulation study showed that sample size, item discrimination, and type of correlation coefficient considerably influence the performance of parallel analysis.