ENA symptom (from Greek σύμπτωμα, "accident, misfortune, that which befalls", from συμπίπτω, "I befall", from συν- "together, with" and πίπτω, "I fall") is a d...
ENA case-control study is a type of observational study in which two existing groups differing in outcome are identified and compared on the basis of some supp...