This figure represents an idea that's important for many areas of science and it's known as the normal (or, sometimes, Gaussian) distribution. Simply put, the idea is that many natural phenomena will be — and have been — observed to vary around some average (the "mean"). All things being equal, we should expect individuals to be about average in most ways — average heights, average intelligence, average shoe size... whatever. If an individual was average in every way, it would be accurate (in statistical terms) to describe her or him as completely normal. But, most people are not entirely average in every way and that's where things get interesting.

Your report includes figures for your scores on all of the SPI 27 Factors, the Big Five, and cognition. For each of these, your score is indicated by the shaded region. The average score for each is a 50 and the standard deviation is 10.

For more information about the normal distribution, try this link.