One frequently needs to compare the performance of two or more parallel computers, but how should this be done? The most straightforward way to do this would be to rely upon a suite of benchmarks. Unfortunately, there are many problems and limitations with this approach. Therefore, one is frequently forced to rely upon a combination of approaches. Unfortunately, many of the alternative approaches are all too frequently based on excessively simplistic approximations and extrapolations. This report discusses some of these issues so that the problems they can cause may be avoided in the future. 11