Correlation vs. Causation

At a meeting/workshop that I was recently at for Baja State's plan of action for climate change (PEAC BC) there was a good and needed comment to one of the presentations. Someone had shown a correlation to heat and lack of water to increase in disease (mainly diarrhea), to which his language seemed to say "droughts and heat spells cause increase in disease." This is not valid, a correlation shows just that, that two things happen at the same time, but not that one is the cause of the other.

For example, on sunny days I like to have a BBQ, and when I cook with charcoal I tend to inhale smoke and that makes me cough. You would see a correlation to sunny days and me coughing. Incorrectly you would conclude that sunny days makes me cough, but the causal relation is that BBQ, and the way I make them, cause smoke inhalation, and that is the cause of coughing.

Correlations are useful in guiding research, but are not causal! Below is a good video outlining this. I'm still skeptical about the final statement about the flu and the H1N1 shot, but that is intuition and I have no real evidence on it. I probably wont get the shots, but that is because I don't know where to here in Mexcio.