Perhaps you should try some spelling variations:
"improving poor performance series." » "improving poor performance metrics.", "improving poor performance reviews.", "improving poor performance review.", "improving export performance series.", "improving sector performance series.", "improving _ performance series.", "improving power performance series.", "improving food performance series.", "improving indoor performance series."
"improving human performance evidence." » "improving loan performance evidence.", "improving thermal performance evidence.", "improving company performance evidence.", "improving urban performance evidence.", "improving rural performance evidence."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving human performance evidence.") or ("improving poor performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving human performance evidence.") OR ("improving poor performance series.")).
• Removing quotes may allow a broader search: (( improving human performance evidence. ) or ( improving poor performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving human performance evidence.") or ("improving poor performance series."))*.