Perhaps you should try some spelling variations:
"improving basic performance standards." » "improving music performance standards.", "improving baseline performance standards.", "improving seismic performance standards.", "improving air performance standards.", "improve basic performance standards."
"improving based performance evidence." » "improving board performance evidence.", "improving fund performance evidence.", "improving good performance evidence.", "improving care performance evidence.", "improving asset performance evidence.", "improving beef performance evidence."

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 basic performance standards.") or ("improving based performance evidence."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving basic performance standards.") OR ("improving based performance evidence.")).
• Removing quotes may allow a broader search: (( improving basic performance standards. ) or ( improving based performance evidence. )).
• Adding a wildcard symbol may retrieve word variants: (("improving basic performance standards.") or ("improving based performance evidence."))*.