Perhaps you should try some spelling variations:
"improving rail performance metrics." » "improving rail performance measures.", "improving raise performance metrics.", "improving railway performance metrics.", "improving pupil performance metrics.", "improving brain performance metrics.", "improving air performance metrics."
"improving social performance review." » "improving school performance review.", "improving fiscal performance review.", "improving financial performance review.", "improving social performance risk.", "improving social 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 social performance review.") or ("improving rail performance metrics."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving social performance review.") OR ("improving rail performance metrics.")).
• Removing quotes may allow a broader search: (( improving social performance review. ) or ( improving rail performance metrics. )).
• Adding a wildcard symbol may retrieve word variants: (("improving social performance review.") or ("improving rail performance metrics."))*.