Last November, I learned the very sad news from Michael Friendly that John Fox had passed away. That brought my memory back to 2006 when I emailed John for the first time asking for his help on a problem about Structural Equation Models (SEM), which had puzzled me for months. I reached out to him because I had seen an appendix on SEM (freely available on his website) in his book, An R and S-PLUS Companion to Applied Regression. He …