To get an idea of whether you should continue to run a Search Network campaign on search partner sites, you can:
use Keyword Planner to evaluate how the campaign might perform better on search partner sites
review the top movers report to see if the campaign is getting more clicks on search partner sites
evaluate the campaign’s performance on search partner sites vs. display partner sites
segment the campaign’s data by network and evaluate its performance on search partner sites
Read more here: https://support.google.com/partners/answer/2404037
https://www.youtube.com/watch?v=fH-sQLyWEvM