Perhaps you should try some spelling variations:
"improving central performance metrics." » "improving contract performance metrics.", "improving sectoral performance metrics.", "improving entry performance metrics.", "improving central performance contracts.", "improving central performance measures.", "improving central performance contract.", "improving mental performance metrics.", "improving critical performance metrics.", "improving energy performance metrics."
"improving high performance series." » "improving high performance reviews.", "improving high performance review.", "improving high performance targets.", "improving firm performance series.", "improving _ performance series.", "improving higher performance series.", "improving hiv performance series.", "improving birth 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 central performance metrics.") or ("improving high performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving central performance metrics.") OR ("improving high performance series."))*.
• Removing quotes may allow a broader search: (( improving central performance metrics. ) or ( improving high performance series. ))*.