I´m not sure of how to calculate the R and S-statistic. If I have a timeserie like this: 10-20-25-30-40.... =X(t) The first R/S: - just two values. avg of X(1) and X(2) = 15 S= of X(1) and X(2) =(10-15)+(20-15) =sqrt(50)=7.1 R=max deviation from mean - min deviation from mean = 5-(-5) = 10 R/S= 10/7.1 =1.4 But how do I proceed now? Do I repeat the process for X(1)-X(2)-X(3) or X(2) -X(3)? If I have a serie of N values, how many R/S can be calculated? N-1 or ? Many Thanks, Jan ================================================================= Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =================================================================