Sample spiral model using the PSM

Two lines with arrow heads intersecting perpendicular to one another to show four quadrants. The top left quadrant is labelled Analysis. The top right quadrant is labelled Design. The bottom right quadrant is labelled Development and the bottom left quadrant is labelled Evaluation. Starting near the origin of the axes in the top left quadrant is an expanding coiled line with an arrowhead at the end. At this point it is labelled Requirements Constraints Scope. This follows through into the top right quadrant and is labelled Design ideas. An arrow points to the bottom right quadrant and is labelled Solution. This follows through to the bottom left quadrant and is labelled feedback. This follows through to the top left quadrant and is labelled Refine Requirements Constraints Scope. This follows through to the top right quadrant and is labelled Detailed designs. An arrow points to the bottom right quadrant and is labelled Refine Solution. This follows through to the bottom left quadrant and is labelled Evaluation. This follows through to the top left quadrant and is labelled Refine Requirements Constraints Scope. This follows through to the top right quadrant and is labelled Detailed designs. An arrow points to the bottom right quadrant and is labelled Refine Solution. This follows through to the bottom left quadrant and is labelled Evaluation.