Building a new Rasch-based self-report inventory of depression

Figures & data

Table 1 Summary of measures of Rasch model fit for 51-item pool and 21-item pool (N=529)

Measures of fit	51-item model	21-item model
Summary item mean (SD)	0.000 (0.417)	0.000 (0.502)
Summary person mean (SD)	−0.589 (1.222)	−0.606 (1.552)
Total item χ^2	868.21	147.71
P (χ^2)	0.000	0.486
Degree of freedom	408	168
PSI	0.977	0.959

Abbreviations: PSI, Person Separation Index; SD, standard deviation.

Table 2 Rasch item analysis, item parameter estimates, and fit statistics of the 21 selected items with correspondent Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision diagnostic criterion (N=529)

Item content	Diagnostic criterion	Location oritem difficulty	SE	Fitresidual	χ^2	P (χ^2)
1. Feeling blue	VII	−0.943	0.07	1.916	10.051	0.24
15. Enjoymenta	I	−0.895	0.06	0.930	6.329	0.60
17. Decisivenessa	VIII	−0.594	0.06	1.380	8.564	0.36
20. Enjoy thingsa	II	−0.566	0.06	−2.201	5.506	0.69
19. Being worthlessa	VII	−0.505	0.06	−0.278	5.483	0.70
8. Concentration abilitya	VIII	−0.387	0.06	−1.066	10.225	0.23
7. Feeling prouda	VII	−0.156	0.06	−0.984	4.959	0.76
11. Loss of self-confidence	VII	−0.130	0.06	1.624	6.847	0.54
14. Lack of energya	VI	−0.094	0.06	−1.239	7.450	0.48
13. Fatigability	VI	−0.089	0.06	0.472	4.484	0.81
16. Energy	VI	−0.012	0.06	−1.410	11.848	0.14
12. Slowing down	V	0.199	0.06	1.434	10.058	0.24
10. Enjoymenta	II	0.245	0.06	−0.443	5.498	0.70
4. Awareness of slowdown	V	0.310	0.06	0.354	7.748	0.44
9. Self-dislike	VII	0.391	0.06	−0.325	6.891	0.54
18. Loss of interest	II	0.412	0.06	0.068	11.238	0.17
2. Concentration difficulty	VIII	0.422	0.06	0.828	1.356	0.99
6. Withdrawal	IX	0.423	0.05	0.561	5.344	0.71
21. Give meaninga	IX	0.536	0.06	−0.440	3.855	0.87
5. Self-shame	VII	0.609	0.06	1.294	11.919	0.13
3. Worth livinga	IX	0.825	0.06	0.004	2.062	0.98

Notes:

a Reverse scored items. Items organized by decreasing difficulty parameter or location. Reprinted with permission from Hogrefe Editore Srl. Balsamo M, Saggino A. TDI - Teate Depression Inventory. Copyright © 2013.⁸⁸

Abbreviation: SE, standard error.

Table 3 Estimates of category thresholds of 21 Teate Depression Inventory items (N=529)

Items	Category threshold estimates
	τi1	τi2	τi3	τi4
1	−2.996	−1.674	0.981	3.688
2	−1.821	−1.054	0.408	2.468
3	−1.060	−0.563	0.411	1.212
4	−2.075	−0.921	0.486	2.510
5	−1.178	−0.646	0.334	1.489
6	−1.145	−0.912	0.150	1.908
7	−2.558	−0.330	0.747	2.142
8	−3.043	−0.197	0.722	2.518
9	−1.298	−0.999	0.229	2.068
10	−2.359	−0.411	0.763	2.007
11	−2.083	−0.854	0.520	2.417
12	−2.172	−0.899	0.525	2.547
13	−2.424	−1.010	0.471	2.962
14	−2.480	−0.245	0.674	2.051
15	−2.843	−0.232	0.727	2.349
16	−2.210	−0.604	0.394	2.420
17	−3.070	0.003	0.815	2.253
18	−1.487	−0.969	0.313	2.143
19	−3.165	−0.218	0.827	2.555
20	−2.870	−0.254	0.567	2.557
21	−1.399	−0.661	0.445	1.615

Table 4 Uniform and nonuniform differential item functioning (DIF) statistics for all Teate Depression Inventory items (N=529)

Item	Uniform DIF				Nonuniform DIF
	Sex				Sex X class interval
	MS	F	df	P	MS	F	df	P
1	5.47	5.166	1	0.023451	1.23	1.163	8	0.319557
2	1.47	1.434	1	0.231645	0.54	0.523	8	0.839351
3	0.04	0.043	1	0.835947	0.59	0.615	8	0.765688
4	0.24	0.244	1	0.621738	0.98	1.013	8	0.425339
5	0.50	0.470	1	0.493101	1.11	1.046	8	0.400433
6	0.08	0.082	1	0.775212	1.04	1.039	8	0.405080
7	0.03	0.029	1	0.865615	0.57	0.634	8	0.749296
8	0.04	0.046	1	0.829384	0.68	0.770	8	0.629441
9	0.36	0.388	1	0.533492	0.77	0.829	8	0.576830
10	10.31	11.397	1	0.000801	0.87	0.967	8	0.461311
11	0.08	0.073	1	0.787262	1.71	1.636	8	0.111815
12	2.93	2.826	1	0.093355	0.98	0.942	8	0.480909
13	0.24	0.247	1	0.619269	1.50	1.537	8	0.141724
14	0.36	0.049	1	0.522685	0.53	0.598	8	0.779465
15	0.61	0.609	1	0.435590	1.28	1.272	8	0.255466
16	1.93	2.305	1	0.129548	1.87	2.233	8	0.023920
17	0.57	0.543	1	0.461709	0.40	0.378	8	0.932538
18	0.05	0.054	1	0.815841	1.94	2.087	8	0.035466
19	0.05	0.049	1	0.825584	0.60	0.637	8	0.747019
20	0.03	0.040	1	0.842438	1.27	1.551	8	0.136952
21	5.26	5.820	1	0.016188	1.27	1.403	8	0.192296

Abbreviation: MS, mean square.

Figure 1 Differential item functioning graph of males and females for Teate Depression Inventory item 10.

Figure 2 The distribution of the group diagnostic person factor across all levels of depression severity.

Note: Reprinted with permission from Hogrefe Editore Srl. Balsamo M, Saggino A. TDI - Teate Depression Inventory. Copyright © 2013.⁸⁸

BalsamoMSagginoATDI - Teate Depression InventoryFirenze, ItalyHogrefe Editore Srl2013 Italian

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