Records

Methodological context for: Bullowa JGM (1928a). The use of antipneumococcic refined serum in lobar pneumonia: data necessary for a comparison between cases treated with serum and cases not so treated, and the importance of a significant control series of cases. JAMA 90:1354-1358.

Allocation bias

Differences between the people compared

 

Play of chance

Taking account of the play of chance