Perhaps you should try some spelling variations:
"processing sampling statistics methods." » "processing spain statistics methods.", "processing sampling statistical methods.", "processing sampling statistics methodology."
"processing digital statistics methods." » "processing vital statistics methods.", "processing capital statistics methods.", "processing criminal statistics methods.", "processing digital statistical methods.", "processing digital statistics methodology."

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• Performing a fuzzy search may retrieve terms with similar spellings: (("processing digital statistics methods.") or ("processing sampling statistics methods."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("processing digital statistics methods.") OR ("processing sampling statistics methods.")).
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