Perhaps you should try some spelling variations:
"improving sectoral performance evidence." » "improving sector performance evidence.", "improving school performance evidence.", "improving social performance evidence.", "improving central performance evidence.", "improving mental performance evidence."
"improving poor performance series." » "improving poor performance metrics.", "improving poor performance reviews.", "improving poor performance review.", "improving export performance series.", "improving sector performance series.", "improving _ performance series.", "improving power performance series.", "improving food performance series.", "improving indoor 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 sectoral performance evidence.") or ("improving poor performance series."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving sectoral performance evidence.") OR ("improving poor performance series.")).
• Removing quotes may allow a broader search: (( improving sectoral performance evidence. ) or ( improving poor performance series. )).
• Adding a wildcard symbol may retrieve word variants: (("improving sectoral performance evidence.") or ("improving poor performance series."))*.