Publication bias in the returns to R&D literature

The returns to R&D literature is large and has been surveyed on several occasions. We complement previous surveys by using formal meta analytic techniques to analyse publication bias. We find evidence consistent with a strong positive bias in the part of the literature that controls for unobserved firm fixed effects. The reason may be that fixed effects specifications are particularly susceptible to measurement errors and therefore have a high probability of producing implausibly low return estimates. Implausible estimates are likely to be filtered out before being reported, and our analysis suggest that 26 % of a hypothetical complete literature is missing. Future reviews should take into account that the full effect of negative specifications biases may be masked by reporting and publication bias.