Positive and Negative Affect Schedule (PANAS)
A 20-item self-report scale commonly used to assess mood, comprising of 10 positive and 10 negative state items. Items are rated on a 5 point Likert scale (1: Not at all, 5: Extremely), with higher scores indicating predominant mood.
Watson, D., Clark, L.A. & Tellegen, A. (1988). Development and validation of brief measures of Positive and Negative Affect: the PANAS Scales. Journal of Personality & Social Psychology, 54 (6), 1063-1070.