I’ve posted Entry #69 to my weekly Valuation-Informed Indexing column at the Value Walk site. It’s called Is Valuation-Informed Indexing the Product of Backtesting?
Juicy Excerpt: Shiller’s research showing that this works dates back to 1981. Shiller’s research is publicly available. So, if you look at what Shiller said should work in 1981 and then look forward to see how well it really did work in the following three decades, that’s front-testing. That should be sufficient to persuade any remaining skeptics.