Fig. 5

Distributions for simulated total depressive symptom scores when the depressive symptoms’ latent traits were set to exponential distributions with a parameter of λ = 2. Exponential distribution with a parameter of λ = 2 was used for the distribution of the latent trait, and normal distributions with standard deviations of 1 (a, c) and 2 (b, d) were applied to distribution of the threshold of depressive symptoms items. a, b With a normal scale and c, d are with a log-normal scale