Nezlek, J. B., & Zebrowski, B. D. (2001). Implications of the dimensionality of unrealistic optimism for the study of perceived health risks. Journal of Social and Clinical Psychology, 20, 520-536.

To examine the dimensions of unrealistic optimism, 635 college students indicated their relative likelihood of experiencing 25 health problems commonly used in studies of unrealistic optimism. Factor analyses of these estimates yielded five correlated, but distinct factors, suggesting that unrealistic optimism is not a unidimensional construct. Two factors, Common and Mixed, were comprised of heterogeneous problems. The Common factor was comprised of problems similar to those frequently used in other studies, and these problems were also perceived as more likely to occur than problems comprising other factors. Three factors were comprised of problems in specific domains, Substance abuse, Sexuality, and Mental health. Participants' psychological well-being and dispositional optimism were negatively correlated with perceived risk of experiencing mental health problems, whereas these measures were unrelated to perceived risks for other types of problems. The present results suggest that results of studies on unrealistic optimism may vary considerably as a function of the specific health risks being examined.