Evidence is insufficient because of: 1  The limited number or size of studies. 2  Important flaws in study design or methods. 3  Inconsistency of findings across individual studies. 4  Gaps in the chain of evidence. 5  Findings not generalizable to routine primary care practice. 6  Lack of information on important health outcomes.
Definition of jerk for English Language Learners. : 1  a stupid person or a person who is not well-liked or who treats other people badly. : 2  a quick pull or twist. : 3  a sudden sharp movement.
Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia. twitch. a brief, contractile response of a skeletal muscle elicited by a single maximal volley of impulses in the neurons supplying it. twitch. 1. To jerk spasmodically. 2. A momentary spasmodic contraction of a muscle fiber.