PrOH Modelling data is collected by interviewing people who work within the system being modelled. The best way to do this is to interview people individually and ask them to tell a story about the process being modelled as they understand it. A skilful interviewer should be able to sketch this process map whilst the interviewer is talking using simple flowcharting and once done will be able to annotate the diagram with strengths, weaknesses and opportunities. This activity should be repeated for six to ten people for each model. Each person should represent a different stakeholder perspective of the system under observation to help reduce personal biases. 

The modeller is then able to construct a consensus viewpoint of the system under observation in a PrOH Model by combining every different tenable perspective together in a single model, or set of models depending how large the system being modelled is. At this point it is a good to use a SIPOC (supplier – input – process – output – customer) type table where the output from one process becomes the input into another process to ensure that logic in process flow has been clarified. Putting many different stakeholder perspectives together in a unified model is a skill – part art and part science. Once the logic in the model has been established the drawing can begin.