Table 2.

Numbers needed to detect a significant difference between TAU and the intervention group for the different psychological instruments.

Instrument	Assumed additional improvement in comparison with TAU (∑ Total points per scale)	Maximum (∑ Total points)	N per group
SIPS	−15	114	17
SPI-CY	−9	84	16
SWE	+4	40	27
GAF	+10	100	24

GAF, Global Assessment of Functioning Scale; SIPS, Structured Interview for Prodromal Syndromes; SPI-CY, Schizophrenia Proneness Interview Child and Youth Version; SWE, General Self-Efficacy Scale; TAU, treatment as usual.