The present invention relates to systems and methods for diagnosing undesirable events or the lack of desirable events representing product or process malfunctions. One aspect of the invention includes a method for determining a cause of a malfunction event in a prototype or production product or process. Another aspect of the invention includes a method for identifying evidence of deviation from a specification for a product or process. Still another aspect of the invention includes a method for ascertaining the reliability of a product or process. The present invention also provides a diagnostic computer system and computer program code for performing various methods embodying different aspects of the present invention. A computer system for training a user to diagnose and apply corrective action to a malfunctioning product or process is also provided.