Not sure where to post this question, but here goes In excel I have calculated the average annual rain for the period 1990-2012 to be 50.2mm . How do you estimate the probability that this measured average (1990-2012) is consistent with the long term mean annual rain for the period 1948-2012 (assuming a gaussian distribution) which I calculated to be 51.6mm? Is there some sort of function or is this simpler than I'm imagining... any help much appreciated thanks
Hi, I've come up with a solution I think. Going to use the NORM.DIST function thanks for the reply though
izzy, The typical test for this is the Student's t-test http://en.wikipedia.org/wiki/Student's_t-test#Independent_two-sample_t-test which determines whether the difference in means between two samples is statistically significant.