  A third way around non-locality is to ‘exploit’ the inefficiency of measurement devices or (more generally) measurement set-ups. In any actual EPR/B experiment, many of the particle pairs emitted from the source fail to be detected, so that only a sample of the particle pairs is observed. Assuming that the observed samples are not biased, it is now generally agreed that the statistical predictions of orthodox quantum mechanics have been vindicated (for a review of these experiments, see Redhead 1987, section 4.5). But if this assumption is abandoned, there are perfectly local causal explanations for the actual experimental results (Clauser and Horne 1974, Fine 1982b, 1989a). Many believe that this way out of non-locality is ad hoc, at least in light of our current knowledge. Moreover, this strategy would fail if the efficiency of measurement devices exceeded a certain threshold (for more details, see Fine 1989a, Maudlin 1994, chapter 6, Larsson and Semitecolos 2000 and Larsson 2002). 