title: Item response theory analysis of the life orientation test-revised: age and gender differential item functioning analyses.
abstract: This study is aimed at testing the measurement properties of the Life Orientation Test-Revised (LOT-R) for the assessment of dispositional optimism by employing item response theory (IRT) analyses. The LOT-R was administered to a large sample of 2,862 Italian adults. First, confirmatory factor analyses demonstrated the theoretical conceptualization of the construct measured by the LOT-R as a single bipolar dimension. Subsequently, IRT analyses for polytomous, ordered response category data were applied to investigate the items' properties. The equivalence of the items across gender and age was assessed by analyzing differential item functioning. Discrimination and severity parameters indicated that all items were able to distinguish people with different levels of optimism and adequately covered the spectrum of the latent trait. Additionally, the LOT-R appears to be gender invariant and, with minor exceptions, age invariant. Results provided evidence that the LOT-R is a reliable and valid measure of dispositional optimism.
authors: University of Milan-Bicocca, Milan, Italy.
authors: Patrizia
authors: P
authors: Steca
authors: University of Milan-Bicocca, Milan, Italy dario.monzani@unimib.it.
authors: Dario
authors: D
authors: Monzani
authors: University of Milan-Bicocca, Milan, Italy.
authors: Andrea
authors: A
authors: Greco
authors: University of Florence, Florence, Italy.
authors: Francesca
authors: F
authors: Chiesi
authors: University of Florence, Florence, Italy.
authors: Caterina
authors: C
authors: Primi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000523:psychology*; D002605:Character; D005260:Female; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D000067656:Optimism / Q000523:psychology*; D009949:Orientation; D010555:Personality Inventory / Q000706:statistics & numerical data*; D011594:Psychometrics / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D012737:Sex Factors; D055815:Young Adult
keywords: Life Orientation Test-Revised; differential item functioning; item equivalence; item response theory; optimism assessment