Table 2.
Item response theory parameters for the items of the Depression, Anxiety and Stress scales of the DASS
| DASS items | Thr1 | Thr2 | Thr3 | Mean Threshold | Discr | ||
|---|---|---|---|---|---|---|---|
| Depression scale | 13 | I felt sad and depressed | −0.07 | 1.49 | 2.51 | 1.31 | 2.87 |
| 26 | I felt down-hearted and blue | 0.08 | 1.56 | 2.60 | 1.41 | 3.38 | |
| 5 | I just couldn’t seem to get going | −0.65 | 1.83 | 3.65 | 1.61 | 1.28 | |
| 42 | I found it difficult to work up the initiative to do things | −0.07 | 1.73 | 3.17 | 1.61 | 1.72 | |
| 10 | I felt that I had nothing to look forward to | 0.55 | 1.73 | 2.66 | 1.65 | 2.79 | |
| 17 | I felt I wasn’t worth much as a person | 0.48 | 1.82 | 2.82 | 1.70 | 2.44 | |
| 37 | I could see nothing in the future to be hopeful about | 0.75 | 1.79 | 2.64 | 1.73 | 3.50 | |
| 34 | I felt I was pretty worthless | 0.70 | 1.89 | 2.76 | 1.78 | 2.94 | |
| 21 | I felt that life wasn’t worthwhile | 0.74 | 1.88 | 2.76 | 1.79 | 3.44 | |
| 38 | I felt that life was meaningless | 0.88 | 1.92 | 2.75 | 1.85 | 3.25 | |
| 24 | I couldn’t seem to get any enjoyment out of the things I did | 0.47 | 2.08 | 3.18 | 1.91 | 2.93 | |
| 31 | I was unable to become enthusiastic about anything | 0.65 | 2.10 | 3.18 | 1.98 | 2.57 | |
| 3 | I couldn’t seem to experience any positive feeling at all | 0.57 | 2.17 | 3.38 | 2.04 | 2.72 | |
| 16 | I felt that I had lost interest in just about everything | 0.91 | 2.28 | 3.31 | 2.16 | 2.82 | |
| Anxiety scale | 20 | I felt scared without any good reason | 0.92 | 2.03 | 3.00 | 1.98 | 2.84 |
| 28 | I felt I was close to panic | 0.91 | 2.05 | 3.08 | 2.01 | 3.36 | |
| 9 | Situations made me so anxious I was most relieved when they ended | 0.86 | 2.04 | 3.14 | 2.02 | 2.59 | |
| 40 | I was worried about situations in which I might panic and make a fool of myself | 0.94 | 2.08 | 3.05 | 2.02 | 2.37 | |
| 36 | I felt terrified | 1.14 | 2.13 | 2.93 | 2.07 | 3.41 | |
| 30 | I feared that I would be “thrown” by some trivial but unfamiliar task | 1.01 | 2.21 | 3.39 | 2.20 | 2.00 | |
| 7 | I had a feeling of shakiness | 0.98 | 2.39 | 3.80 | 2.39 | 2.00 | |
| 25 | I was aware of the action of my heart in the absence of physical exertion | 0.70 | 2.56 | 4.33 | 2.53 | 1.24 | |
| 2 | I was aware of dryness of my mouth | 0.63 | 2.73 | 4.67 | 2.68 | 1.03 | |
| 4 | I experienced breathing difficulty | 1.13 | 2.65 | 4.28 | 2.69 | 1.59 | |
| 41 | I experienced trembling | 1.49 | 2.85 | 3.74 | 2.69 | 1.87 | |
| 19 | I perspired noticeably in the absence of high temperatures or physical exertion | 1.20 | 2.80 | 4.39 | 2.80 | 1.29 | |
| 15 | I had a feeling of faintness | 1.78 | 3.49 | 4.93 | 3.40 | 1.66 | |
| 23 | I had difficulty in swallowing | 2.06 | 3.66 | 5.02 | 3.58 | 1.48 | |
| Stress scale | 8 | I found it difficult to relax | −0.62 | 1.16 | 2.38 | 0.97 | 1.84 |
| 27 | I found that I was very irritable | −0.30 | 1.39 | 2.69 | 1.26 | 2.90 | |
| 18 | I felt that I was rather touchy | −0.37 | 1.44 | 2.86 | 1.31 | 2.62 | |
| 39 | I found myself getting agitated | −0.05 | 1.51 | 2.79 | 1.41 | 2.16 | |
| 6 | I tended to over-react to situations | −0.20 | 1.58 | 3.03 | 1.47 | 2.44 | |
| 11 | I found myself getting upset rather easily | 0.27 | 1.54 | 2.82 | 1.54 | 2.94 | |
| 29 | I found it hard to calm down after something upset me | 0.33 | 1.70 | 2.76 | 1.59 | 2.36 | |
| 12 | I felt that I was using a lot of nervous energy | 0.11 | 1.72 | 3.03 | 1.62 | 2.43 | |
| 1 | I found myself getting upset by quite trivial things | 0.01 | 1.74 | 3.23 | 1.66 | 2.17 | |
| 35 | I was intolerant of anything that kept me from getting on with what I was doing | 0.17 | 1.90 | 3.26 | 1.78 | 1.83 | |
| 14 | I found myself getting impatient when I was delayed in any way | −0.34 | 1.96 | 3.79 | 1.80 | 1.12 | |
| 33 | I was in a state of nervous tension | 0.47 | 1.98 | 3.25 | 1.90 | 1.95 | |
| 32 | I found it difficult to tolerate interruptions to what I was doing | 0.10 | 2.19 | 4.01 | 2.10 | 1.27 | |
| 22 | I found it hard to wind down | 0.53 | 2.58 | 4.32 | 2.47 | 1.41 | |
Per scale, items are ordered in ascending order by mean threshold
Thr1 = response threshold between category 0 and 1; Thr2 = threshold between response category 2 and 3; Thr3 = threshold between response category 3 and 4; Discr = item discrimination parameter