Perhaps you should try some spelling variations:
"proceso contralos statistical methods." » "proceso control statistical methods.", "proceso contra statistical methods.", "proces contreles statistical methods.", "procesos contables statistical methods."
"process control estadisticas methods." » "process control estadistica methods.", "process control estadistico methods.", "process control statistical methods.", "process control estadisticas metodos.", "process control estadisticas datos.", "process control estadisticas medicas.", "procesos control estadisticas methods.", "procesal control estadisticas methods."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("process control estadisticas methods.") or ("proceso contralos statistical methods."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("process control estadisticas methods.") OR ("proceso contralos statistical methods."))*.
• Removing quotes may allow a broader search: (( process control estadisticas methods. ) or ( proceso contralos statistical methods. ))*.