Open Brainstorms

Do a SWAT analyzes on they ideas or general direction of ideas

experientially score Ideas that invert, 180 degree shits, perspective and paradigm shift, on the basis of novelty and discomfort

The number of ideas not necessarily required to be discarded. These are the ideas that are discarded based more on bureaucratic (did I get the spelling right ?) factors rather than the functionality point of view

creativity of the ideas, i.e., how crazy are they . This factor wil eventually add to the innovation quotient in the idea

"why didn't i think of it" factor? A-ha moments

number of ideas spun-off or built upon from the original idea

disruptiveness

technological readiness

feasibility and perhaps arguably IP generated would be reasonable parameters, as suggested by abandvc. i would have to disagree that number of people, diversity, and/or certainly speed are valuable measurement metrics. instead, i would add that the degree that a "brainstorm" can transform/resolve the objective set out in the first place -- e.g. "brainstorming" is often the result of searching for a solution to a problem or a set of problems -- would likely be the prime indicator of "quality"

Speed of idea generation (500 ideas/hr, etc.)

Patentability/Intellectual Property value generated

Novelty of the ideas

Number of people involved/ diversity of ideas

Feasibility level of the ideas