title: Factor structure of the Positive and Negative Affect Schedule (PANAS) in adult women with fibromyalgia from Southern Spain: the al-Ándalus project.
abstract: BACKGROUND
  Fibromyalgia is a syndrome characterized by the presence of widespread chronic pain. People with fibromyalgia report lower levels of Positive Affect and higher levels of Negative Affect than non-fibromyalgia peers. The Positive and Negative Affect Schedule (PANAS)-a widely used questionnaire to assess two core domains of affect; namely 'Positive Affect' and 'Negative Affect' -has a controversial factor structure varying across studies. The internal structure of a measurement instrument has an impact on the meaning and validity of its score. Therefore, the aim of the present study was to assess the structural construct validity of the PANAS in adult women with fibromyalgia.
  
  
  METHODS
  This population-based cross-sectional study included 442 adult women with fibromyalgia (age: 51.3 ± 7.4 years old) from Andalusia (Southern Spain). Confirmatory factor analyses were conducted to test the factor structure of the PANAS.
  
  
  RESULTS
  A structure with two correlated factors (Positive Affect and Negative Affect) obtained the best fit; S-B χ(2) = 288.49, df = 155, p < .001; RMSEA = .04; 90% CI of RMSEA = (.036, .052); the best fit SRMR = .05; CFI = .96; CAIC = -810.66, respectively.
  
  
  CONCLUSIONS
  The present study demonstrates that both Positive Affect and Negative Affect are core dimensions of affect in adult women with fibromyalgia. A structure with two correlated factors of the PANAS emerged from our sample of women with fibromyalgia from Andalusia (Southern Spain). In this model, the amount of variance shared by Positive Affect and Negative Affect was small. Therefore, our findings support to use and interpret the Positive Affect and Negative Affect subscales of the PANAS as separate factors that are associated but distinctive as well.
authors.affiliation: Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain; Department of Psychology, Faculty of Social and Behavioural Sciences, Utrecht University, Utrecht, The Netherlands.
authors.forename: Fernando
authors.identifier: 0000-0003-2960-4142
authors.initials: F
authors.lastname: Estévez-López
authors.affiliation: Department of Psychology, Faculty of Humanities and Education Sciences, University of Jaén , Jaén , Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Pulido-Martos
authors.affiliation: Manchester Centre for Health Psychology, School of Psychological Sciences, Manchester Academic Health Science Centre, University of Manchester , Manchester , United Kingdom.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Armitage
authors.affiliation: Manchester Centre for Health Psychology, School of Psychological Sciences, Manchester Academic Health Science Centre, University of Manchester , Manchester , United Kingdom.
authors.forename: Alison
authors.initials: A
authors.lastname: Wearden
authors.affiliation: Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada , Granada , Spain.
authors.forename: Inmaculada C
authors.initials: IC
authors.lastname: Álvarez-Gallardo
authors.affiliation: Department of Physical Education, Music and Fine Arts, Faculty of Education Sciences, University of Huelva , Huelva , Spain.
authors.forename: Manuel Javier
authors.initials: MJ
authors.lastname: Arrayás-Grajera
authors.affiliation: Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada , Granada , Spain.
authors.forename: María J
authors.initials: MJ
authors.lastname: Girela-Rejón
authors.affiliation: Department of Physical Education, Faculty of Education Sciences, University of Cádiz , Cádiz , Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Carbonell-Baeza
authors.affiliation: Department of Physiology and Institute of Nutrition and Food Technology, Faculty of Pharmacy, University of Granada, Granada, Spain; Department of Public and Occupational Health, EMGO+ Institute for Health and Care Research, VU University Medical Care, Amsterdam, The Netherlands.
authors.forename: Virginia A
authors.initials: VA
authors.lastname: Aparicio
authors.affiliation: Department of Psychology, Faculty of Social and Behavioural Sciences, Utrecht University , Utrecht , The Netherlands.
authors.forename: Rinie
authors.initials: R
authors.lastname: Geenen
authors.affiliation: Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada , Granada , Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Delgado-Fernández
authors.affiliation: Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain; Department of Physical Education, Faculty of Education Sciences, University of Cádiz, Cádiz, Spain.
authors.forename: Víctor
authors.identifier: 0000-0001-8655-9857
authors.initials: V
authors.lastname: Segura-Jiménez
keywords: Affectivity; Chronic pain; Confirmatory factor analysis; Dimensional structure; Emotion; Mood; Positive and Negative Affect Schedule; Psychometrics