Value investing is a well-regarded investment strategy with its roots tracing back several centuries. However, it was only in the 20th century that it began to crystallise into a formalised approach, with a significant milestone being the publication of "Security Analysis" by Benjamin Graham and David Dodd in the 1930s. This book introduced a method to ascertain a company's intrinsic value based on its Earnings Per Share (EPS) and long-term growth prospects. Graham further refined this approach in his subsequent book "The Intelligent Investor" (1974), though the essence of the strategy remained intact.

The core idea of value investing revolves around the "value factor," which is a fundamental component of factor investing. It posits that stocks priced below their intrinsic value have a higher likelihood of outperforming those priced at a premium over time. This hypothesis is anchored in the assertion that market inefficiencies can result in mispricing, thus creating opportunities for astute value investors to achieve superior returns.

The pivotal research by Eugene Fama and Kenneth French in 1992, titled "The Cross-Section of Expected Stock Returns," lent empirical support to the value factor. Their findings illustrated that portfolios consisting of stocks with low price-to-book (P/B) ratios tended to outperform those with high P/B ratios over an extended period.

Since then, the value factor has attracted considerable attention in the academic realm, fostering a robust body of research. Scholars have not only corroborated the legitimacy of the value factor but also delineated various metrics to gauge it, such as Price-to-Earnings (P/E), Price-to-Book (P/B), Price-to-Sales (P/S), Price-to-Cash Flow (P/CF), Enterprise Value to Earnings Before Interest, Taxes, Depreciation, and Amortized Expenses (EV/EBITDA), and Dividend Yield, among others.

It's noteworthy to mention that while the value factor has showcased its potential to yield superior returns over the long haul, value investing carries its set of risks. Value stocks may display heightened volatility in comparison to growth stocks, and there could be phases where they lag. Hence, investors are advised to understand and carefully navigate the intricacies and trade-offs embedded in the pursuit of value-centric strategies.