%0 Journal Article %A J M Stephenson %A A Babiker %T Overview of study design in clinical epidemiology %D 2000 %R 10.1136/sti.76.4.244 %J Sexually Transmitted Infections %P 244-247 %V 76 %N 4 %U https://sti.bmj.com/content/sextrans/76/4/244.full.pdf