RT Journal Article SR Electronic T1 Study design and statistical analysis: a practical guide for clinicians JF Clinical Medicine JO Clin Med FD Royal College of Physicians SP 111 OP 112 DO 10.7861/clinmedicine.8-1-111a VO 8 IS 1 A1 Caroline A Sabin YR 2008 UL http://www.rcpjournals.org/content/8/1/111.2.abstract AB