premise: In guitar music, especially electric guitar, a power chord    (also fifth chord) is a colloquial name for a chord that consists of the root note and the fifth. Power chords are commonly played on amplified guitars, especially on electric guitar with distortion. Power chords are a key element of many styles of rock and especially in heavy metal, and punk rock.
hypothesis: Power chords are played in more than amplified guitars 
reason: They are commonly played in amplified guitars, but not only