Perhaps you should try some spelling variations:
"improving living performance metrics." » "improving living performance measures.", "improving driving performance metrics.", "improving firing performance metrics.", "improving mixing performance metrics.", "improve living performance metrics.", "improving learning performance metrics.", "improving reading performance metrics."
"improving rural performance series." » "improving rural performance studies.", "improving rural performance size.", "improving euract performance series.", "improving larval performance series.", "improving pupil 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 rural performance series.") or ("improving living performance metrics."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving rural performance series.") OR ("improving living performance metrics.")).
• Removing quotes may allow a broader search: (( improving rural performance series. ) or ( improving living performance metrics. )).
• Adding a wildcard symbol may retrieve word variants: (("improving rural performance series.") or ("improving living performance metrics."))*.