Correlation Does Not Equal Causation T-Shirt Solid colors: 100% Cotton; Heather Grey: 90% Cotton, 10% Polyester; All Other Heathers: 50% Cotton, 50% Polyester Imported Machine wash cold with like colors, dry low heat Correlation doesn't imply cause quote on a shirt for a scientist or psychologist who likes experiments Scientific tee for science or math geeks that understand variables and constants Lightweight, Classic fit, Double-needle sleeve and bottom hem