Questionnaire is etymologically related to Question. Question is a synonym of Inquiry. Poll is a type of Inquiry. 
Statistics is related to Average. Average is related to Term. Term is related to Double. 
Questionnaire --EtymologicallyRelatedTo--> Question <--Synonym--> Inquiry <--IsA-- Poll 
Statistics <--RelatedTo--> Average <--RelatedTo--> Term <--RelatedTo--> Double 