“…Moreover, we do not assume that the intraday patterns are the same across different days of the week but do estimation for each of them separately. This is also different from most of previous studies, some of which allow but do not detect weakly seasonal components, e.g., Bauwens and Giot (2000), although Grammig and Wellner (2002) and Bauwens, Giot, Grammig, and Veredas (2004) also condition both on timeof-day and on day-of-week. An extreme position is taken in Meitz and Teräsvirta (2003), where splines are fit separately for each day of the sample.…”