RT Journal Article SR Electronic T1 How to read a paper: Statistics for the non-statistician. I: Different types of data need different statistical tests JF BMJ JO BMJ FD British Medical Journal Publishing Group SP 364 OP 366 DO 10.1136/bmj.315.7104.364 VO 315 IS 7104 A1 Greenhalgh, Trisha YR 1997 UL http://www.bmj.com/content/315/7104/364.abstract AB