WordNet records no synonym and no antonym for nonparametric statistics. It is the only member of its synset, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
the branch of statistics dealing with variables without making assumptions about the form or the parameters of their distribution
Synonyms, antonyms and the broader and narrower relations for nonparametric statistics come from Princeton University’s WordNet. Full sources and licences.