Comparing these results with the corresponding "Pseudo pos only" results, we can see that  additionally employing negative pseudo-instances consistently improves performance: F-scores rise by 0.8-4.1% on Pine and 3.0-4.9% on World-VistA.
the improvements in F-score in three of the six cases (Pine/Baseline, World-VistA/manual, WorldVistA/induced) are statistically significant.