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 risk." » "improving loan performance risk.", "improving thermal performance risk.", "improving company performance risk.", "improving human performance size.", "improving human performance based.", "improving human performance _.", "improving urban performance risk.", "improving rural performance risk."

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