“…We note that average weekly price of June 1994 serves as the price of the base period, and its value is set to 100, which indicates fifty-kilogram’s price of wholesale yellow corn. Table 1 presents the usual summary statistics of the prices, where we could see that they do not follow normal distributions like most of financial time series (Xu, 2017, Xu, 2019; Xu & Zhang, 2022, Xu & Zhang, 2022). Finally, we note that the price index is missing on February 19, 2010, and we apply the cubic spline interpolation technique for an approximated value of 122.839, which is rather close to 122.85 on February 12, 2010, and 122.53 on February 26, 2010.…”