I've tried to reproduce the data/graphs mentioned in the following article: http://www.zealllc.com/2002/vola.htm The basic definition of 'volatility' as used in the article is (High-Low) divided by Yesterday's Close. Then this raw data is smoothed using a simple 25 day moving average. Seems simple right? But somehow I don't get the same result. Not even close! But I think I've done the spreadsheet correctly (see below). I would appreciate if anyone would take a look at this and maybe find what I've missed or done incorrectly. Thanks in advance. btw...I truncated the data as it would have been too big to upload.