http://www.wikiwebapp.com/share.html#w/244B814C-F696-458D-A66A-B971886C9542

https://www.mathsisfun.com/data/scatter-xy-plots.html

http://mste.illinois.edu/courses/ci330ms/youtsey/scatterinfo.html

http://www.spcforexcel.com/knowledge/root-cause-analysis/correlation-analysis