  This is a report about the use and misuse of citation data in the assessment
of scientific research. The idea that research assessment must be done using
``simple and objective'' methods is increasingly prevalent today. The ``simple
and objective'' methods are broadly interpreted as bibliometrics, that is,
citation data and the statistics derived from them. There is a belief that
citation statistics are inherently more accurate because they substitute simple
numbers for complex judgments, and hence overcome the possible subjectivity of
peer review. But this belief is unfounded.
