Correctness is binary, while quality is not.
replyCorrectness is a suitable property to act as a multiplier in your formula, where incorrect is 0 and correct is 1, but you also need other facets to find a quality gradient.
In this context it's not binary. Context is everything. If it was binary there would only be 0 and 1 on one of the axis in the graph. That's not the case.
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