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Table 2 Item slope a and item locations b 1 , b 2 , and b 3 , stratified by language and ethnicity

From: Cross-cultural validation of the German and Turkish versions of the PHQ-9: an IRT approach

Item Samplea a (SE) b 1 (SE) b 2 (SE) b 3 (SE)
1. Anhedonia G-G 2.93 (0.17) −0.49 (0.04) 0.92 (0.07) 1.54 (0.10)
T-G 2.59 (0.35) −0.45 (0.12) 1.15 (0.14) 1.85 (0.20)
T-T 1.45 (0.32) −0.52 (0.29) 1.46 (0.26) 2.06 (0.34)
2. Depressed mood G-G 3.97 (0.26) −0.26 (0.04) 0.83 (0.06) 1.47 (0.10)
T-G 3.46 (0.51) −0.13 (0.10) 0.80 (0.11) 1.51 (0.15)
T-T 4.16 (0.84) −0.13 (0.13) 0.88 (0.18) 1.26 (0.22)
3. Sleep problems G-G 2.54 (0.14) −0.60 (0.04) 0.63 (0.06) 1.31 (0.09)
T-G 2.37 (0.32) −0.47 (0.13) 0.55 (0.11) 1.34 (0.16)
T-T 2.33 (0.48) −0.48 (0.20) 0.67 (0.18) 1.02 (0.21)
4. Low energy G-G 3.02 (0.17) −0.83 (0.04) 0.56 (0.06) 1.32 (0.09)
T-G 2.94 (0.40) −0.84 (0.13) 0.43 (0.10) 1.22 (0.14)
T-T 2.95 (0.61) −0.78 (0.23) 0.77 (0.17) 1.12 (0.21)
5. Appetite changes G-G 2.53 (0.16) 0.04 (0.05) 1.08 (0.08) 2.07 (0.15)
T-G 2.40 (0.34) 0.00 (0.11) 0.81 (0.12) 1.55 (0.18)
T-T 1.57 (0.36) 0.07 (0.20) 1.59 (0.30) 1.88 (0.34)
6. Low self-esteem G-G 3.04 (0.20) 0.05 (0.04) 0.93 (0.07) 1.54 (0.11)
T-G 2.95 (0.44) 0.14 (0.10) 1.01 (0.12) 1.62 (0.17)
T-T 2.97 (0.64) 0.03 (0.14) 1.13 (0.21) 1.51 (0.26)
7. Concentration difficulties G-G 2.92 (0.19) 0.08 (0.05) 1.07 (0.08) 1.89 (0.13)
T-G 2.08 (0.30) 0.09 (0.11) 0.98 (0.14) 1.75 (0.21)
T-T 2.33 (0.51) 0.33 (0.15) 1.27 (0.23) 1.93 (0.32)
8. Psychomotor changes G-G 2.32 (0.17) 0.63 (0.07) 1.64 (0.13) 2.39 (0.20)
T-G 2.67 (0.43) 0.56 (0.11) 1.51 (0.17) 2.04 (0.23)
T-T 2.76 (0.64) 0.25 (0.14) 1.25 (0.22) 1.58 (0.27)
9. Suicidal ideation G-G 2.74 (0.23) 0.79 (0.07) 1.64 (0.12) 2.29 (0.19)
T-G 2.40 (0.42) 1.02 (0.13) 1.71 (0.20) 2.28 (0.29)
T-T 2.06 (0.52) 0.90 (0.18) 1.86 (0.32) 2.08 (0.36)
  1. Bolded data where DIF (see Table 3) is present
  2. aG-G Germans with no migration background completing the German version of the PHQ-9 (n = 1670), T-G Turkish immigrants completing the German version of the PHQ-9 (n = 191), T-T Turkish immigrants completing the Turkish version of the PHQ-9 (n = 116)