Perhaps you should try some spelling variations:
"improving do performance metrics." » "improving do performance measures.", "improving di performance metrics.", "improving 2 performance metrics.", "improving 3 performance metrics.", "improving co performance metrics.", "improving eco performance metrics.", "improving pro performance metrics."
"improving labor performance series." » "improving labor performance studies.", "improving labor performance size.", "improving poor performance series.", "improving bar performance series.", "improving donor performance series.", "improving land performance series.", "improving air performance series.", "improve labor performance series."

Try widening your search to All Fields.

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

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