  In narrative synthesis of evidence, it can be the case that the only
quantitative measures available concerning the efficacy of an intervention is
the direction of the effect, i.e. whether it is positive or negative. In such
situations, the sign test has been proposed in the literature and in recent
Cochrane guidelines as a way to test whether the proportion of positive effects
is favourable. I argue that the sign test is inappropriate in this context as
the data are not generated according to the Binomial distribution it employs. I
demonstrate possible consequences for both hypothesis testing and estimation
via hypothetical examples.
