A computer system has an input system and an output system. Program code to be debugged has a plurality of program code statements. The input system is utilized to indicate an error variable in the program code. The error variable has an error value that differs from a desired value. An error set of the error variable is obtained, which is a subset of the statements in the computer readable code. Each statement in the error set is relationally connected to the error variable. A priority value is given to each statement in the error set. The priority values indicate a computed probability that the associated statement is an error source of the error variable. Finally, the output system is used to present each statement in the error set in an ordered manner according to the priority values.