4. LISREL and Its Progeny

Sewall Wright’s path coefficients were conceived as dimensionless binary indicators of whether a genetic trait was passed to an offspring, or not. Correlations in Wright’s context were almost overkill, though their magnitude might have been considered to suggest varying degrees of confidence in heritability of a trait. As path analysis began to find application in analyzing relationships that were multivalued or continuous, limitations in the ability to resolve effects began to reveal themselves. It was in this context that Tukey (1954) advocated systematic replacement in path analysis of the dimensionless path coefficients by the corresponding concrete path regressions. Geneticists Turner and Stevens (1959) published their seminal paper presenting the mathematics of path regression and inviting extensions that would apply other developments in statistics. In the early days of data processing, both Herman Wold and his student Karl Jöreskog developed software, building on Turner and Stevens’ mathematics, that took advantage of computer-intensive techniques becoming available to universities in the 1970s and 1980s.