Before computers, statisticians used methods that were computationally tractable, at the cost of known limitations. Since the 1980s these approximate statistical methods have been discarded. Modern twin methods based on structural equation modeling are not subject to the limitations and heritability estimates such as those noted above are mathematically impossible.M. C. Neale, S. M. Boker, G. Xie and H. H. Maes. (2002). Mx: Statistical Modelling. Journal. Critically, the newer methods allow for explicit testing of the role of different pathways and incorporation and testing of complex effects.
Before computers, statisticians used methods that were computationally tractable, at the cost of known ,limitations. Since the 19,80s these approximate statistical methods have been discarded. Modern twin methods based on structural equation modeling are not subject to the limitations and heritability estimates such as those noted above are mathematically impossible.M. C. Neale, S. M. Boker, G. Xie and H. H. Maes. (2002). Mx: Statistical Modelling. Journal. Critically, the newer methods allow for explicit testing! of the role of different pathways and incorporation and testing of complex effects.