Perhaps you should try some spelling variations:
"improving co performance metrics." » "improving co performance measures.", "improving ceo performance metrics.", "improving do performance metrics.", "improving core performance metrics.", "improving eco performance metrics.", "improving crop performance metrics.", "improving ict performance metrics."
"improving worker performance series." » "improving work performance series.", "improving market performance series.", "improving poor performance series.", "improving worker performance studies.", "improving worker performance size.", "improving water 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 worker performance series.") or ("improving co performance metrics."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving worker performance series.") OR ("improving co performance metrics.")).
• Removing quotes may allow a broader search: (( improving worker performance series. ) or ( improving co performance metrics. )).
• Adding a wildcard symbol may retrieve word variants: (("improving worker performance series.") or ("improving co performance metrics."))*.