Source: http://rlisu.files.wordpress.com/2009/11/immigration.jpg http://www.csulb.edu/~msaintg/ppa696/696sampl.htm#Simple
Please view the video by clicking the link below:
http://videos.howstuffworks.com/hsw/22970-discovering-math-bias-in-sampling-video.htm
A brief look at sampling in the real world.