This working document reports on a randomized controlled experiment that tested the influence of different process strategies on the added value of an urban planning support system (PSS) called Urban Strategy. The experiment involved dividing students into control and treatment groups to complete a planning task. Treatment A involved full PSS support with a mediator structuring the process as brainstorm-analyze-feedback-redesign. Treatment B involved the same full support but with the process structured as personal thinking-analyze-role based redesign. Evaluation results found that Treatment B scored higher than A on most perceived quality dimensions, though few differences were statistically significant. Sensitivity to the treatments varied by participant background, with environmental/transport engineering students more positive about Treatment B's process quality and us