Abstract: The present disclosure provides methods for accurately predicting the dynamics of symptom response to drugs or other interventions for the treatment of major depressive disorder or other psychological conditions. These methods can allow for a shortening of the time period necessary for the evaluation of a drug or other therapeutic intervention. These predictive methods are based on measured and/or self-reported symptom severity measures at two or more points in time. These measures are then discretized into symptom classes (e.g., low, moderate, severe) and the symptom classes are then applied to the predictive model to predict the progression of symptoms and/or the effectiveness of a drug or other therapeutic intervention.