Perhaps you should try some spelling variations:
"improving rural performance metrics." » "improving rural performance contracts.", "improving rural performance measures.", "improving rural performance contract.", "improving pupil performance metrics.", "improving thermal performance metrics.", "improving overall performance metrics.", "improving urban performance metrics.", "improving social performance metrics."
"improving birth performance evidence." » "improving firm performance evidence.", "improving high performance evidence.", "improving port performance evidence.", "improving air performance evidence.", "improving health performance evidence.", "improving growth performance evidence."

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

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