“…In addition, note that the bivariate approach also allows us to measure investors' uncertainty, derived from conditional volatility of sentiment, simultaneously with the volatility of stock markets. In this regard, our study is also different from the few studies that exist associated with in-sample and out-of-sample predictability of stock market volatility based on primarily the new papers-based measure of economic uncertainty, derived from outside the econometric model associated with volatility (e.g., see Liu and Zhang (2015), Su et al (2017Su et al ( , 2019, Fang et al (2018), and Li et al (2019)). Modeling joint dynamics is important, given the findings of recent studies (e.g., see Mumtaz and Theodoridis (2020) and Ludvigson, Ma, and Ng (2015)), which indicates that uncertainty is in fact endogenous rather than exogenous.…”