We picked up on Hans Rosling's documentary, 'The Joy of Stats', where we left off several weeks ago. Today, he covered the most interesting topic of correlation analysis. Correlations can be found between almost any two random things - there are whole websites devoted to this, mostly humorous, but they illustrate how dangerous it can be if people without the mathematical skills to understand correlations start trying to draw conclusions between datasets. However, the science of correlations underlies much of statistics. As an example, I used my work from my astrophysics days to show a correlation analysis undertaken on radio, soft X-ray, and hard X-ray emission from a black hole X-ray binary, and how we were able to conclude that previously thought unrelated emission processes were, in fact, traceable to a common physical origin (for the first time ever).