This article clarifies the use of statistics to describe the success of inf
ertility treatments, with specific emphasis on assisted reproductive techno
logy. A discussion of the January 2000 Society for Assisted Reproductive Te
chnology/Centers for Disease Control report for procedures performed in 199
7 is included. Limitations on the use of statistical analysis and the probl
em of multiple gestation are addressed. A glossary of terms is included for
reference.