The Exceptionality of Twice-Exceptionality: Examining Combined Prevalence of Giftedness and Disability Using Multivariate Statistical Simulation

Twice-exceptionality (2e), broadly defined as the co-occurrence of a gift or talent and a disability, has been a part of the educational lexicon since the 1990s, although its empirical backing is limited. We conducted a comprehensive review of the empirical literature on 2e and created a simulation study of 2e. For the latter, we constructed population distribution functions that represent indicators of ability using a range of correlations and identification criteria guided by the reviewed literature. We observed the theoretical occurrence of 2e, even at its most relaxed definitions, to be much rarer than prevailing literature implies (probability = 0.148). As correlations and factor loadings increase, the prevalence estimates of 2e drop considerably. Our results demonstrated the need for a more informed, standardized, and quantifiable approach to the identification of individuals with 2e.