The International Positive and Negative Affect Schedule Short Form (I-PANAS-SF): Dimensionality, Factorial Invariance, Reliability, and Utility for Discriminating Depression and Anxiety Caseness in a Large Spanish Sample

The Positive and Negative Affect Schedule (PANAS) is widely used to assess positive affect (PA) and negative affect (NA). An international short-form version (I-PANAS-SF) was created for cross-cultural research. This study evaluates the validity and reliability of its Spanish version. This cross-sectional study involved 2,120 Spanish-speaking adults. We examined the structural, convergent, cross-groups, known-groups, and criterion validity, along with internal consistency and test–retest reliability. A two-factor model (PA and NA) showed excellent fit (CFI = 0.97, TLI = 0.96, RMSEA = 0.07). Measurement invariance across sex, age, depression, and anxiety groups was found. Correlations with depression, anxiety, stress, life satisfaction, and subjective happiness were as expected. The I-PANAS-SF discriminated between individuals with/without possible major depression or general anxiety disorder. Reliability and stability were adequate (PA: ω = .85, ICC = 0.80; NA: ω = .75, ICC = 0.75). The Spanish I-PANAS-SF is a valid and reliable tool for assessing affect in Spanish-speaking adults.