Table 3.

PHQ-2 (scale: [0–6]) prediction and forecasting results, reported as mean-average-error (MAE) and Spearman’s $\rho$ correlation using the four methods: (B)aseline-GRU without personalisation, (T)ransfer (L)earning, (S)ubgroup models, and (S)ubject-(D)ependent (S)tandardisation.

Method	Prediction		Forecasting
	MAE	$\rho$	MAE	$\rho$
B	1.062	0.604	1.539	0.105
TL	0.990	0.668	1.349	0.349
S	0.978	0.666	1.465	0.271
SDS	0.801	0.728	1.496	0.254