Clarification of the mirage method for boundary correction, with possible bias in plot and point sampling

While the mirage method of boundary overlap correction has been shown to be unbiased, an emphasis on the case of circular inclusion zones has led to an ambiguity in its presentation in much of the literature, We present a clarification of the method and show that its incorrect application leads to bias. We further show that depending on the method of slope correction, the potential for bias extends to variable radius plot sampling, Correct application of the mirage method has implications for when plots should be reflected, and how borderline trees should be handled on the reflected plots.