Table 3 Item-fit statistics for the 9Q product and 9QSF combination items’ suitability for the GRM by using chi2W item-fit statistics (adult participants; N = 1,355)

Mood (χ²=25.57, p<0.001)

Mood (χ²=39.37, p<0.001)

Interest (χ²=1.75, p=0.186)

Interest (χ²=6.48, p=0.011)

Sleep (χ²=7.57, p=0.006)

Sleep (χ²=9.28, p=0.002)

Fatigue (χ²=4.90, p=0.027)

Fatigue (χ²=4.49, p=0.034)

Weight (χ²=5.98, p=0.015)

Weight (χ²=10.46, p=0.001)

Guilt (χ²=1.37, p=0.241)

Guilt (χ²=7.07, p=0.008)

Concentration (χ²=4.76, p=0.029)

Concentration (χ²=9.96, p=0.002)

Psychomotor (χ²=3.07, p=0.080)

Psychomotor (χ²=3.21, p=0.073)

Suicide (χ²=22.79, p<0.001)

Suicide (χ²=45.38, p<0.001)