Problem Trends Why Hard? Syllabus And one more No historical usage information to allow measurement, evaluation and improvement of standard designs over time Always specially constructed Usually doing new things Copyright Nancy Leveson, Sept 1999��������������������������� Problem Trends Why Hard? Slyllabus And One More � � � � � � � � � � � � � � � � � � � � � � � � � � � No historical usage information to allow measurement, evaluation, and improvement of standard designs over time. Always specially constructed. Usually doing new things. c Copyright Nancy Leveson, Sept. 1999 �