Perhaps you should try some spelling variations:
"improving national performance reviews." » "improving regional performance reviews.", "improving operational performance reviews.", "improving educational performance reviews.", "improving national performance review.", "improving national performance reports.", "improving national performance risks.", "improving maternal performance reviews.", "improving natural performance reviews.", "improve national performance reviews."
"improving thermal performance metrics." » "improving thermal performance measures.", "improving external performance metrics.", "improving animal performance metrics.", "improving erm performance metrics."

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

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