This on-line web application will create a response time curve, calculate the associated math based on a Unit Of Work Time Based Analysis (UOWTBA); all based on data available from an Oracle AWR or Statspack report. There is also a cool link to WolframAlpha.com that will create the response time graph!
This technical paper and these presentations will provide more details about this tool; the need, how to use in real life, etc.
This tool is used in OraPub's Advanced Oracle Performance Analysis course and it's One-Day Performance Seminars.
This tool can be used in conjunction with the last chapter of Craig's book, Oracle Performance Firefighting.