Eisner (2009) suggests that developer-led evaluations often make programs look better than independent evaluations do because the former suffer systematic biases in favor of prevention success. However, his proposed remedies suffer their own systematic bias, constituting a "one-tailed" test of bias in only one direction. This response suggests that a more objective assessment of analysts' effects requires a "two-tailed" test of bias, in which reviewers would measure indications of bias both for and against success in evaluations reported by both developers and independent evaluators. Specifically, the article explores the complex nuances of key concepts that both Eisner and other commentators fail to define adequately, it presents a fifth case for Eisner documenting the "negative developer effect" it proposes a set of indicators of analysts' biases against finding crime prevention effects, and it suggests that, if any assessment of analysts' bias is added to systematic reviews, it should be conducted in the proposed two-tailed framework. Table, figures, and references