Input-process-output (I-P-O) is a structured methodology for capturing and visualizing all of the inputs, outputs, and process steps that are required to transform inputs into outputs.

Desensitize and Control Your Product or Process Output Variation. We want to focus our time and apply our resources to those input variables that desensitize and control our output variation.

Mechanical control systems (staplers, car windows) use parts for movement/force control. They include input, process, and output. Types of motion: linear, rotary, reciprocating, oscillating.

Donald P. Ballou, Harold L. Pazer, Modeling Data and Process Quality in Multi-Input, Multi-Output Information Systems, Management Science, Vol. 31, No. 2 (Feb., 1985), pp. 150-162 Free online reading ...