[Tripartite Influence Scale (TIS) applied to university students: validation study and application]

The Tripartite Influence Scale (TIS) is used to assess the influence of social and family factors on individuals' body image. However, little evidence has been presented on the validity of the TIS construct. The study aimed to estimate the psychometric indicators in TIS and identify the degree of influence of the media, parents, and peers on body image in university students, considering different characteristics. University students of both sexes participated. The psychometric indicators in TIS were assessed for each sex using confirmatory factor analysis. Mean scores were calculated for each TIS factor. Prevalence rates for degree of influence were presented. A multivariate regression model was built to verify the relationship between target characteristics and TIS factor scores. The sample included 791 university students (63.2% women) 18 to 40 years of age. TIS did not initially display a good fit to the samples and was therefore refined. After refinement, the scale showed adequate validity and reliability for women and men. Significant differences were observed in the mean scores between women and men, and in the prevalence rates the majority of the students were in the low category. Work, consumption of food supplements for body changes, age, body mass index, self-rated diet, and level of physical activity were significantly related to TIS factors. Women were generally more influenced than men by the media and peers. Characteristics identified as related to TIS can be relevant for inclusion in clinical and research protocols.