“…(1) is defined either as the difference in prices (e.g., BW93) or as the log return (e.g., Chakravarty et al, 2005), and the length of t varies from several months (e.g., Ascioglu, Comerton-Forde, & McInish, 2011) to a few hours (e.g., Blau, Van Ness, & Van Ness, 2009a). Some studies choose stocks with Δp t s N 0 (e.g., Chakravarty, 2001), while some others ignore the sign of Δp t s (e.g., O'Hara et al, 2014).…”