 Based on these data, it is hypothesized that the rapid augmentation in exogenous variables (such as increasing R&D expenditure or specific policy initiatives (viz. , Bayh Dole, Stevenson-Wydler) are the key impetuses behind the increase of persistencyduring Period 2. Post-1990s exogenic variables led to the maintenance of the high degree and consistency of the persistency metric.
<meaning-changed>  Based on these data, it is hypothesized that the rapid augmentation in exogenous variables (such as increasing R&D expenditure or specific policy initiatives (viz. , Bayh Dole, Stevenson-Wydler) are the key impetuses behind the increase of persistencyduring Period 2. Post-1990s exogenic variables led to the maintenance of the high degree and consistency of the persistency metric.
 Based on these data, it is hypothesized that the rapid augmentation in exogenous variables (such as increasing R&D expenditure or specific policy initiatives (viz. , Bayh Dole, Stevenson-Wydler) are the key impetuses behind persistency, latent in PTA. The post-1990s exogenic factors seem to be simply maintaining the high degree and consistency of the persistency metric.