Abstract
Background: Depression is a disorder that is highly prevalent nowadays. Within the dimensional explanatory model of depression, the State/Trait Depression Inventory was developed. Its objective is to identify the degree of affectation (state) and the frequency of occurrence (trait) of the affective component of depression. The instrument has proven reliable and comprises two factors in its structure: state and trait, with two euthymia and dysthymia subscales in each one. The objective of this meta-analysis is to find an average alpha for the questionnaire. Method: A bibliographical search was conducted on Web of Science and Scopus. Forty-five articles were selected. Results: The alpha ranges from .84 to .89 for all factorizations, and in most studies a bifactorial structure of state and trait depression was found. Conclusions: The State/Trait Depression Inventory is a reliable and suitable instrument for measuring depression.
