(Note 19/10/09 – this post is getting a lot of hits at the moment, but I don’t know why.  Its not generating any comments and its ceratainly not my best post – visitors please feel to leave a calling card in the comments and let me know why you are here).

This post is a follow-on to my previous post about stones and erosion.  It is more practical, fortunately you might say, but still relies on analogy, if not stories.  I like analogy.

So here is the analogy.  We know that a diet high in fruit and vegetables is healthy.  We now why it is healthy and we know roughly how much consumption of fruit and veg = healthy (five portions per day).  However – you cannot take a single carrot and measure how much it adds to our healthiness.  Consumption of one carrot cannot be correlated to an additional x milliseconds of life for example and any attempts to do so would be a classic example of misuse of statistical evidence.  Likewise, we know that physical fitness correlates to health but we can’t measure the impact of one session at the gym. Continue reading →