Mental Toughness Inventory: Factorial validity and ethnic group measurement equivalence in competitive tennis

The Mental Toughness Inventory (MTI) has obtained preliminary support as a psychometrically valid unidimensional measure of mental toughness. Initially developed and validated using a variety of Australian sub-groups, this study explored the cultural and sport-specific applicability of the instrument to competitive male (n = 249) South African tennis players (M-age = 17.84, SD = 2.51). The fit indices from the confirmatory factor analyses largely supported the factor structure of the MTI among the total sample and each of the white (n = 120) and non-white (n = 129) ethnic groupings. The comparative fit indices also provided evidence of the configural, metric, scalar, and strict invariance of the MTI across the groups. Mental toughness scores correlated positively with dispositional hope, and the MTI was found to be internally reliable. Collectively, the findings provide additional psychometric support for using the MTI as a brief, unidimensional measure of mental toughness, extending the utility of the instrument to an underexplored sociocultural context (South Africa) and sport-specific domain (tennis).