Unfortunately, when it comes to understanding random phenomena, our intuition often lets us down. Take a look at the image below. Before you read the caption, see if you can pick out the data set generated using truly uniform random numbers for the coordinates of the dots (i.e., for each point, independent of the others, the horizontal coordinate is equally likely to fall anywhere along the horizontal axis and the vertical coordinate is equally likely to fall anywhere along the vertical)
From – Behavioural Scientist.