Perhaps you should try some spelling variations:
"improving mental performance metrics." » "improving mental performance measures.", "improving general performance metrics.", "improving senegal performance metrics.", "improving annual performance metrics.", "improving maternal performance metrics.", "improving fiscal performance metrics.", "improving gender performance metrics."
"improving urban performance series." » "improving urban performance studies.", "improving urban performance size.", "improving bank performance series.", "improving loan performance series.", "improving human performance series."

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

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