hello, I have plots http://uosis.mif.vu.lt/~roka5178/time series.JPG I must to do almost the same. I do not have any data. but i know that this is time series data with parabolic changeable mean. I can not generate tie series data with parabolic mean. how can i do this? and have http://uosis.mif.vu.lt/~roka5178/time series2.JPG with paarbilic changeable standart. -- Robertas [[alternative HTML version deleted]]