I have been going in rounds with this problem... I may be thinking "complicated", any advice?
I have the mean and total sample size (=number of data points) and I need to know what is the standard deviation (SD).
I know I can calculate back the sum of individual scores from the formal formula for calculation of the mean, i.e.:
M = Σ(X) / N
where X=individual data points N=number of data points
However after this step I am stuck. To find the SD using the variance I need to know the individual data points and which I don't have.
I then end up with two "unknown" variables, S2 and X in this formula:
S2 = Σ(X-M) 2 / N - 1
Thank you André and Jonathan. I now got some extra information: I am given the N and mean(maximum), e.g.: N=596, mean(maximum): 5.86(39.1); any extra advice?