“…The temporal structure in volatilities is complex and still regarded as an open problem. Return interval τ , also called recurrence time or interspike interval, which is the time interval between two consecutive volatilities above a certain threshold q, provides a new approach to analyze long-term correlated time series [13,14,15,16,17,18,19,20,21,22,23,24]. Recent studies on financial markets [17,18,19,20,21] show that, for both daily and intraday data, i) the distribution of scaled interval τ / τ can be approximated by a single scaling function, where τ is the average of τ .…”