Great topic. I had to dig through all of my fearful stats days to do trending a few years back with SSRS 2005 as we were not going to be buying add on tools... So there I was building my own trend lines.

It isn't just trending where lack of understanding can bite us. To many people write reports with no understanding of the data and far more consume the reports with even less understanding. It is so frightening the number of business decisions that are made with invalid, incorrect, and incomplete data.