The requirements traceability matrix (RTM) supports many software engineering and software verification and validation (V&V) activities such as change impact analysis, reverse engineering, reuse, and regression testing. The generation of RTMs is tedious and error-prone, though, thus RTMs are often not generated or maintained. Automated techniques have been developed to generate candidate RTMs with some success. When using RTMs to support the V&V of mission- or safety-critical systems, however, a human analyst must vet the candidate RTMs. The focus thus becomes the quality of the final RTM. This paper investigates how human analysts perform when vetting candidate RTMs. Specifically, a study was undertaken at two universities and had 26 participants analyze RTMs of varying accuracy for a Java code formatter program. The study found that humans tend to move their candidate RTM toward the line that represents recall = precision. Participants who examined RTMs with low recall and low precision drastically improved both.