Figure 1:

Two-Factor Measurement Model of the Patient Health Questionnaire-9 (PHQ-9).On the right, the boxes represent the PHQ-9 items (indicator variables). Circular arrows that point back to the indicator variables represent item error variances. Moving to the left, unidirectional linear arrows pointing from circles to boxes represent standardized factor loadings. The circles represent latent factors. Circular arrows that point back to the latent factors represents latent variances (fixed to 1.0 for identification purposes, as demonstrated by the asterisk). The bidirectional arrow between latent factors represents a correlation