3.1 General demographics
One hundred twenty-one patients with NPC were included in this study; all patients completed the first and third surveys, including 112 patients who completed the second survey (see Table 1 for general demographic data). The respondents were all Han nationality with the following characteristics: 91 males and 30 females; average age, 48.88 ± 12.32 years; the occupations mainly included workers and farmers; the education level was mainly junior high school, followed by elementary school and high school or technical secondary school; most patients had social insurance (including urban employee medical and urban resident insurance); the family economic status was mainly poor or average, and a few are good; most of the per capita monthly income is < 3000 yuan.
Table 1
General demographic data (n = 121)
Item | Group | n | n% |
Sex | Male | 91 | 75.2 |
Female | 30 | 24.8 |
Nation | Han | 121 | 100.0 |
Career | Worker | 21 | 17.4 |
Farmer | 55 | 45.4 |
Teacher | 4 | 3.3 |
Civil servant | 3 | 2.5 |
Individual | 12 | 9.9 |
Other | 26 | 21.5 |
Education | Primary school | 36 | 29.8 |
Junior high school | 41 | 33.8 |
High school or technical secondary school | 30 | 24.8 |
Junior college | 12 | 9.9 |
Bachelor degree and above | 2 | 1.7 |
Economic status | Poor | 54 | 44.6 |
Moderate | 55 | 45.5 |
Good | 12 | 9.9 |
Per capita monthly income | Below 1000 yuan | 27 | 22.3 |
1000–2000 yuan | 45 | 37.2 |
2000–3000 yuan | 29 | 24.0 |
3000–5000 yuan | 17 | 14.0 |
Above 5000 yuan | 3 | 2.5 |
Medical form | Own expense | 11 | 9.1 |
Social insurance | 88 | 72.7 |
Other | 22 | 18.2 |
3.2 Distribution Of Item Scores
Table 2 shows the distribution of item scores. GPH6, GPH7, GPS3, GPS4, GSO1, GSO2, GSO7, GSS1, GSS2, GSS3, GSS4, GSS5, GSS6, SNA1, SNA2, SNA3, SNA4, SNA5, SNA6, SNA7, SNA8, SNA9, SNA10, and SNA11 had a ceiling effect, while GSO5, SNA3, and SNA4 had a floor effect.
Table 2
Distribution of item scores
Item | Score distribution | Option distribution (the frequency of each value) | Ceiling effect % | Floor effect % | Normality analysis |
code | Mean | Standard Deviation | Median | 1 | 2 | 3 | 4 | 5 | Skewness | Kurtosis |
GPH1 | 2.81 | 0.99 | 3 | 13 | 30 | 49 | 25 | 4 | 3% | 11% | -0.07 | -0.44 |
GPH2 | 3.00 | 0.87 | 3 | 4 | 29 | 55 | 29 | 4 | 3% | 3% | 0.00 | -0.18 |
GPH3 | 3.14 | 1.17 | 3 | 11 | 22 | 47 | 21 | 20 | 17% | 9% | 0.01 | -0.66 |
GPH4 | 3.21 | 0.64 | 3 | 2 | 7 | 78 | 32 | 2 | 2% | 2% | -0.22 | 1.79 |
GPH5 | 3.45 | 1.11 | 3 | 8 | 11 | 44 | 34 | 24 | 20% | 7% | -0.39 | -0.30 |
GPH6 | 4.28 | 0.95 | 5 | 2 | 4 | 18 | 31 | 66 | 55% | 2% | -1.30 | 1.28 |
GPH7 | 4.31 | 1.08 | 5 | 3 | 8 | 15 | 18 | 77 | 64% | 2% | -1.45 | 1.10 |
GPH8 | 3.33 | 0.55 | 3 | 0 | 3 | 74 | 39 | 2 | 2% | 0% | 0.56 | 0.07 |
GPS1 | 3.55 | 1.12 | 4 | 3 | 22 | 31 | 36 | 29 | 24% | 2% | -0.26 | -0.92 |
GPS2 | 2.77 | 0.96 | 3 | 14 | 27 | 56 | 21 | 3 | 2% | 12% | -0.16 | -0.25 |
GPS3 | 4.31 | 0.86 | 5 | 0 | 4 | 19 | 34 | 64 | 53% | 0% | -0.96 | -0.07 |
GPS4 | 4.36 | 0.98 | 5 | 3 | 3 | 16 | 24 | 75 | 62% | 2% | -1.61 | 2.22 |
GPS5 | 2.90 | 1.01 | 3 | 9 | 35 | 42 | 29 | 6 | 5% | 7% | 0.05 | -0.57 |
GPS6 | 3.17 | 1.02 | 3 | 7 | 21 | 50 | 31 | 12 | 10% | 6% | -0.10 | -0.29 |
GPS7 | 3.13 | 0.90 | 3 | 4 | 22 | 57 | 30 | 8 | 7% | 3% | 0.01 | -0.01 |
GPS8 | 2.95 | 1.06 | 3 | 11 | 27 | 51 | 21 | 11 | 9% | 9% | 0.10 | -0.33 |
GPS9 | 3.81 | 0.83 | 4 | 0 | 5 | 40 | 49 | 27 | 22% | 0% | -0.08 | -0.77 |
GSO1 | 4.24 | 0.76 | 4 | 0 | 3 | 15 | 53 | 50 | 41% | 0% | -0.78 | 0.21 |
GSO2 | 3.75 | 0.99 | 4 | 1 | 11 | 38 | 38 | 33 | 27% | 1% | -0.28 | -0.72 |
GSO3 | 3.53 | 1.01 | 4 | 5 | 9 | 46 | 39 | 22 | 18% | 4% | -0.38 | -0.01 |
GSO4 | 2.96 | 1.02 | 3 | 8 | 31 | 50 | 22 | 10 | 8% | 7% | 0.18 | -0.29 |
GSO5 | 2.48 | 1.19 | 2 | 31 | 37 | 20 | 30 | 3 | 2% | 26% | 0.26 | -1.19 |
GSO6 | 2.66 | 1.13 | 3 | 20 | 37 | 35 | 22 | 7 | 6% | 17% | 0.24 | -0.71 |
GSO7 | 4.21 | 0.69 | 4 | 0 | 0 | 18 | 59 | 44 | 36% | 0% | -0.30 | -0.85 |
GSO8 | 3.10 | 1.00 | 3 | 7 | 22 | 55 | 26 | 11 | 9% | 6% | 0.01 | -0.14 |
GSS1 | 4.53 | 0.97 | 5 | 3 | 5 | 8 | 14 | 91 | 75% | 2% | -2.19 | 4.14 |
GSS2 | 3.92 | 1.24 | 4 | 8 | 9 | 23 | 26 | 55 | 45% | 7% | -0.93 | -0.16 |
GSS3 | 4.44 | 0.97 | 5 | 3 | 5 | 9 | 23 | 81 | 67% | 2% | -1.92 | 3.19 |
GSS4 | 3.71 | 1.21 | 4 | 4 | 20 | 26 | 28 | 43 | 36% | 3% | -0.46 | -0.96 |
GSS5 | 3.74 | 1.30 | 4 | 7 | 19 | 22 | 24 | 49 | 40% | 6% | -0.59 | -0.91 |
GSS6 | 3.59 | 1.20 | 4 | 4 | 23 | 28 | 30 | 36 | 30% | 3% | -0.31 | -1.05 |
GSS7 | 3.10 | 1.14 | 3 | 5 | 40 | 31 | 28 | 17 | 14% | 4% | 0.22 | -0.99 |
SNA1 | 4.21 | 1.16 | 5 | 2 | 14 | 16 | 13 | 76 | 63% | 12% | -1.16 | -0.07 |
SNA2 | 3.51 | 1.28 | 3 | 9 | 18 | 34 | 22 | 38 | 31% | 15% | -0.33 | -0.97 |
SNA3 | 3.41 | 1.26 | 4 | 8 | 26 | 26 | 30 | 31 | 26% | 21% | -0.24 | -1.09 |
SNA4 | 3.59 | 1.20 | 4 | 3 | 26 | 26 | 29 | 37 | 31% | 21% | -0.27 | -1.18 |
SNA5 | 3.96 | 1.19 | 4 | 4 | 15 | 19 | 27 | 56 | 46% | 12% | -0.85 | -0.44 |
SNA6 | 4.40 | 1.11 | 5 | 5 | 6 | 12 | 11 | 87 | 72% | 5% | -1.79 | 2.16 |
SNA7 | 3.98 | 1.24 | 4 | 6 | 13 | 19 | 23 | 60 | 50% | 11% | -0.94 | -0.31 |
SNA8 | 4.02 | 1.26 | 5 | 7 | 12 | 16 | 23 | 63 | 52% | 10% | -1.05 | -0.09 |
SNA9 | 4.17 | 1.25 | 5 | 5 | 14 | 13 | 13 | 76 | 63% | 12% | -1.21 | -0.07 |
SNA10 | 4.55 | 0.99 | 5 | 4 | 5 | 5 | 14 | 93 | 77% | 4% | -2.37 | 4.86 |
SNA11 | 4.49 | 0.90 | 5 | 2 | 2 | 15 | 18 | 84 | 69% | 2% | -1.84 | 3.09 |
3.3 Item Characteristics Analysis
The analysis of item characteristics is shown in Table 3. The total Cronbach's α of the scale was 0.90; the Cronbach α did not increase significantly after deleting any item. Item domain-related aspects (GPS4, GSO4, SNA1, and SNA3) had low relevance to the field, and the remaining items had good relevance to the field and were > 0.4, except for items SNA1 and SNA8. The discrimination of GSO4, SNA1, SNA4, and SNA8 was not good, the discrimination of SNA2 and SNA10 was not very good, and the discrimination of other items was good. It was recommended to delete the following entries: GPS4; GSO4; SNA1; SNA3; SNA4; and SNA8.
Table 3
Item characteristics analysis
Item | Alpha if item removed | Correction related of items and fields | Squared multiple correlation | Discrimination | Range of correlation coefficients with other fields |
code |
GPH1 | 0.896 | 0.74 | 0.75 | 0.59 | 0.235−0.363 |
GPH2 | 0.897 | 0.71 | 0.70 | 0.56 | 0.262−0.454 |
GPH3 | 0.897 | 0.56 | 0.61 | 0.53 | 0.187−0.430 |
GPH4 | 0.898 | 0.63 | 0.76 | 0.44 | 0.137−0.480 |
GPH5 | 0.894 | 0.77 | 0.70 | 0.70 | 0.361−0.580 |
GPH6 | 0.896 | 0.75 | 0.72 | 0.61 | 0.148−0.514 |
GPH7 | 0.895 | 0.67 | 0.60 | 0.63 | 0.291−0.484 |
GPH8 | 0.899 | 0.56 | 0.70 | 0.37 | 0.014−0.341 |
GPS1 | 0.897 | 0.79 | 0.68 | 0.52 | 0.103−0.410 |
GPS2 | 0.896 | 0.76 | 0.69 | 0.57 | 0.044−0.559 |
GPS3 | 0.897 | 0.49 | 0.57 | 0.50 | 0.235−0.492 |
GPS4 | 0.898 | 0.43 | 0.65 | 0.49 | 0.183−0.464 |
GPS5 | 0.899 | 0.66 | 0.62 | 0.37 | 0.018−0.460 |
GPS6 | 0.897 | 0.73 | 0.76 | 0.49 | 0.089−0.585 |
GPS7 | 0.898 | 0.63 | 0.60 | 0.43 | 0.043−0.495 |
GPS8 | 0.898 | 0.67 | 0.60 | 0.42 | 0.152−0.292 |
GPS9 | 0.897 | 0.48 | 0.67 | 0.53 | 0.266−0.482 |
GSO1 | 0.897 | 0.73 | 0.68 | 0.55 | 0.139−0.485 |
GSO2 | 0.897 | 0.71 | 0.60 | 0.52 | 0.097−0.713 |
GSO3 | 0.898 | 0.71 | 0.65 | 0.42 | 0.059−0.485 |
GSO4 | 0.905 | 0.02 | 0.45 | 0.12 | 0.052−0.166 |
GSO5 | 0.899 | 0.58 | 0.53 | 0.39 | 0.047−0.368 |
GSO6 | 0.899 | 0.56 | 0.63 | 0.39 | 0.001−0.375 |
GSO7 | 0.899 | 0.62 | 0.54 | 0.41 | 0.05−0.403 |
GSO8 | 0.896 | 0.79 | 0.76 | 0.60 | 0.055−0.582 |
GSS1 | 0.897 | 0.59 | 0.54 | 0.49 | 0.151−0.397 |
GSS2 | 0.896 | 0.77 | 0.59 | 0.56 | 0.272−0.454 |
GSS3 | 0.897 | 0.67 | 0.63 | 0.54 | 0.027−0.400 |
GSS4 | 0.895 | 0.62 | 0.63 | 0.62 | 0.302−0.523 |
GSS5 | 0.898 | 0.72 | 0.64 | 0.48 | 0.100−0.401 |
GSS6 | 0.896 | 0.68 | 0.74 | 0.58 | 0.220−0.521 |
GSS7 | 0.895 | 0.67 | 0.62 | 0.62 | 0.291−0.539 |
SNA1 | 0.906 | 0.11 | 0.55 | 0.08 | 0.019−0.206 |
SNA2 | 0.901 | 0.52 | 0.45 | 0.26 | 0.054−0.259 |
SNA3 | 0.896 | 0.56 | 0.74 | 0.59 | 0.226−0.639 |
SNA4 | 0.903 | 0.47 | 0.51 | 0.13 | 0.060−0.169 |
SNA5 | 0.898 | 0.59 | 0.64 | 0.44 | 0.127−0.311 |
SNA6 | 0.900 | 0.66 | 0.63 | 0.31 | 0.028−0.179 |
SNA7 | 0.895 | 0.63 | 0.73 | 0.64 | 0.220−0.608 |
SNA8 | 0.905 | 0.26 | 0.41 | 0.05 | 0.027−0.095 |
SNA9 | 0.898 | 0.58 | 0.68 | 0.44 | 0.129−0.355 |
SNA10 | 0.901 | 0.64 | 0.68 | 0.22 | 0.009−0.167 |
SNA11 | 0.898 | 0.67 | 0.71 | 0.49 | 0.063−0.418 |
3.4 Items And Parameters Estimations
The first characteristic root-to-the second characteristic root ratio in the total table was 10.40:4.55 (< 3), which did not meet the one-dimensional condition of IRT. Each field met the one-dimensional condition and item analysis was carried out by using the IRT. As shown in Table 4, the discriminative power index of all items ranged from 1.02–1.68 (all > 0.3). GPH4, GPH8, GPS3, GPS9, GSO1, and GSO2, and specific modules (except SNA2) had relatively low difficulty indices. All Bi items increased monotonously between − 2.95 and 2.95, indicating that the classification of items was more reasonable; thus, with an increase in the item level, the difficulty of items also gradually increased.
Table 4
Items and parameters estimations
Item | Discriminative powder index A(S.E.) | B1(S.E.) | B2(S.E.) | B3(S.E.) | B4(S.E.) |
GPH1 | 1.68 (0.08) | -1.77 (0.27) | -0.52 (0.18) | 1.00 (0.21) | 2.75 (0.46) |
GPH2 | 1.68 (0.08) | -2.71 (0.46) | -0.86 (0.18) | 0.83 (0.22) | 2.76 (0.44) |
GPH3 | 1.68 (0.08) | -1.80 (0.30) | -0.76 (0.17) | 0.56 (0.16) | 1.28 (0.21) |
GPH4 | 1.68 (0.08) | -3.24 (0.69) | -2.06 (0.32) | 0.80 (0.20) | 3.21 (0.63) |
GPH5 | 1.68 (0.08) | -2.17 (0.34) | -1.43 (0.22) | 0.04 (0.17) | 1.19 (0.23) |
GPH6 | 1.68 (0.08) | -3.28 (0.69) | -2.40 (0.42) | -1.15 (0.22) | -0.13 (0.18) |
GPH7 | 1.68 (0.08) | -2.94 (0.53) | -1.91 (0.29) | -1.10 (0.21) | -0.48 (0.18) |
GPH8 | 1.68 (0.08) | -6.34 (1.41) | -2.93 (0.96) | 0.58 (0.18) | 3.20 (0.63) |
GPS1 | 1.50 (0.06) | -3.06 (0.54) | -1.26 (0.23) | -0.17 (0.20) | 1.10 (0.24) |
GPS2 | 1.50 (0.06) | -1.82 (0.30) | -0.62 (0.21) | 1.31 (0.24) | 3.20 (0.59) |
GPS3 | 1.50 (0.06) | -6.17 (1.45) | -2.70 (1.35) | -1.28 (0.28) | -0.15 (0.19) |
GPS4 | 1.50 (0.06) | -2.96 (0.51) | -2.44 (0.40) | -1.32 (0.23) | -0.48 (0.18) |
GPS5 | 1.50 (0.06) | -2.18 (0.34) | -0.50 (0.21) | 0.83 (0.19) | 2.56 (0.44) |
GPS6 | 1.50 (0.06) | -2.40 (0.41) | -1.07 (0.23) | 0.58 (0.21) | 2.02 (0.29) |
GPS7 | 1.50 (0.06) | -2.83 (0.48) | -1.19 (0.23) | 0.71 (0.21) | 2.35 (0.37) |
GPS8 | 1.50 (0.06) | -2.01 (0.30) | -0.74 (0.21) | 0.95 (0.21) | 2.08 (0.30) |
GPS9 | 1.50 (0.06) | -6.27 (2.01) | -2.54 (1.07) | -0.47 (0.25) | 1.13 (0.22) |
GSO1 | 1.25 (0.05) | -7.49 (1.21) | -3.59 (2.16) | -1.83 (0.49) | 0.38 (0.30) |
GSO2 | 1.25 (0.05) | -4.44 (1.14) | -2.22 (0.36) | -0.39 (0.23) | 1.01 (0.27) |
GSO3 | 1.25 (0.05) | -3.07 (0.54) | -2.06 (0.34) | -0.04 (0.22) | 1.57 (0.30) |
GSO4 | 1.25 (0.05) | -2.32 (0.38) | -0.69 (0.20) | 0.94 (0.22) | 2.15 (0.35) |
GSO5 | 1.25 (0.05) | -1.08 (0.25) | 0.26 (0.22) | 1.01 (0.24) | 3.49 (0.65) |
GSO6 | 1.25 (0.05) | -1.65 (0.27) | -0.20 (0.22) | 1.09 (0.26) | 2.68 (0.46) |
GSO7 | 1.25 (0.05) | -2.64 (0.43) | -1.39 (0.23) | 0.57 (0.21) | 1.80 (0.45) |
GSO8 | 1.25 (0.05) | -2.78 (0.46) | -1.23 (0.27) | 0.87 (0.29) | 2.39 (0.38) |
GSS1 | 1.60 (0.09) | -2.95 (0.56) | -2.19 (0.35) | -1.60 (0.25) | -0.98 (0.20) |
GSS2 | 1.60 (0.09) | -2.25 (0.34) | -1.60 (0.25) | -0.68 (0.19) | 0.16 (0.20) |
GSS3 | 1.60 (0.09) | -2.96 (0.55) | -2.22 (0.35) | -1.57 (0.26) | -0.62 (0.20) |
GSS4 | 1.60 (0.09) | -2.66 (0.42) | -1.29 (0.19) | -0.38 (0.19) | 0.51 (0.18) |
GSS5 | 1.60 (0.09) | -2.36 (0.35) | -1.17 (0.23) | -0.39 (0.18) | 0.33 (0.19) |
GSS6 | 1.60 (0.09) | -2.76 (0.45) | -1.16 (0.21) | -0.23 (0.18) | 0.75 (0.21) |
GSS7 | 1.60 (0.09) | -2.58 (0.39) | -0.51 (0.17) | 0.42 (0.19) | 1.58 (0.26) |
SNA1 | 1.02 (0.05) | -4.23 (0.96) | -2.05 (0.34) | -1.20 (0.26) | -0.68 (0.25) |
SNA2 | 1.02 (0.05) | -2.84 (0.51) | -1.42 (0.30) | 0.01 (0.25) | 0.90 (0.29) |
SNA3 | 1.02 (0.05) | -3.01 (0.54) | -1.05 (0.30) | 0.03 (0.25) | 1.27 (0.30) |
SNA4 | 1.02 (0.05) | -4.10 (0.89) | -1.29 (0.30) | -0.20 (0.25) | 0.93 (0.29) |
SNA5 | 1.02 (0.05) | -3.84 (0.74) | -1.98 (0.35) | -0.95 (0.29) | 0.18 (0.26) |
SNA6 | 1.02 (0.05) | -3.61 (0.70) | -2.65 (0.46) | -1.66 (0.36) | -1.05 (0.31) |
SNA7 | 1.02 (0.05) | -3.40 (0.60) | -1.98 (0.37) | -0.92 (0.29) | 0.05 (0.27) |
SNA8 | 1.02 (0.05) | -3.00 (0.60) | -1.77 (0.34) | -0.98 (0.24) | -0.14 (0.24) |
SNA9 | 1.02 (0.05) | -3.56 (0.71) | -1.87 (0.38) | -1.10 (0.30) | -0.54 (0.26) |
SNA10 | 1.02 (0.05) | -3.85 (0.78) | -2.88 (0.52) | -2.34 (0.41) | -1.36 (0.34) |
SNA11 | 1.02 (0.05) | -4.62 (1.10) | -3.82 (0.76) | -1.94 (0.37) | -0.92 (0.31) |
3.5 Item Information Estimation
As shown in Table 5, most item information of the GPH, GPS, GSO, and GSS modules (except GOS1) was excellent or good, while the item information for the SNA module is poor. It was therefore recommended to delete GOS1 and SNA1–11; however, because deleting too many items has a great impact on the information content of the scale, items SNA6 and SNA10 with the information content of SNA was < 0.2 were deleted and the remaining items were retained.
Table 5
Item information estimation
| θ | | |
Item | -2 | -1 | 0 | 1 | 2 | On average | level |
GPH1 | 0.71 | 0.82 | 0.77 | 0.77 | 0.71 | 0.75 | Excellent |
GPH2 | 0.69 | 0.77 | 0.72 | 0.76 | 0.66 | 0.72 | Excellent |
GPH3 | 0.73 | 0.85 | 0.81 | 0.85 | 0.51 | 0.75 | Excellent |
GPH4 | 0.77 | 0.44 | 0.52 | 0.72 | 0.52 | 0.59 | Excellent |
GPH5 | 0.83 | 0.80 | 0.82 | 0.81 | 0.46 | 0.74 | Excellent |
GPH6 | 0.83 | 0.85 | 0.75 | 0.32 | 0.08 | 0.57 | Good |
GPH7 | 0.87 | 0.88 | 0.63 | 0.20 | 0.04 | 0.53 | Good |
GPH8 | 0.43 | 0.26 | 0.58 | 0.66 | 0.46 | 0.48 | Good |
GPS1 | 0.59 | 0.68 | 0.68 | 0.63 | 0.37 | 0.59 | Excellent |
GPS2 | 0.59 | 0.67 | 0.59 | 0.61 | 0.58 | 0.61 | Excellent |
GPS3 | 0.65 | 0.68 | 0.60 | 0.29 | 0.08 | 0.46 | Good |
GPS4 | 0.70 | 0.69 | 0.52 | 0.20 | 0.05 | 0.43 | Good |
GPS5 | 0.61 | 0.62 | 0.66 | 0.64 | 0.61 | 0.63 | Excellent |
GPS6 | 0.65 | 0.65 | 0.62 | 0.65 | 0.62 | 0.64 | Excellent |
GPS7 | 0.62 | 0.62 | 0.63 | 0.63 | 0.62 | 0.62 | Excellent |
GPS8 | 0.59 | 0.66 | 0.61 | 0.66 | 0.64 | 0.63 | Excellent |
GPS9 | 0.57 | 0.58 | 0.63 | 0.62 | 0.38 | 0.55 | Good |
GSO1 | 0.44 | 0.44 | 0.42 | 0.34 | 0.16 | 0.36 | Poor |
GSO2 | 0.44 | 0.44 | 0.46 | 0.43 | 0.28 | 0.41 | Good |
GSO3 | 0.47 | 0.42 | 0.45 | 0.45 | 0.38 | 0.43 | Good |
GSO4 | 0.44 | 0.46 | 0.46 | 0.47 | 0.45 | 0.45 | Good |
GSO5 | 0.29 | 0.44 | 0.48 | 0.46 | 0.38 | 0.41 | Good |
GSO6 | 0.39 | 0.46 | 0.47 | 0.47 | 0.45 | 0.45 | Good |
GSO7 | 0.60 | 0.53 | 0.43 | 0.37 | 0.19 | 0.42 | Good |
GSO8 | 0.45 | 0.43 | 0.42 | 0.45 | 0.45 | 0.44 | Good |
GSS1 | 0.82 | 0.74 | 0.37 | 0.10 | 0.02 | 0.41 | Good |
GSS2 | 0.74 | 0.80 | 0.75 | 0.43 | 0.12 | 0.57 | Good |
GSS3 | 0.81 | 0.77 | 0.51 | 0.17 | 0.04 | 0.46 | Good |
GSS4 | 0.72 | 0.78 | 0.78 | 0.57 | 0.20 | 0.61 | Excellent |
GSS5 | 0.74 | 0.79 | 0.78 | 0.50 | 0.16 | 0.59 | Excellent |
GSS6 | 0.69 | 0.77 | 0.78 | 0.65 | 0.27 | 0.63 | Excellent |
GSS7 | 0.62 | 0.65 | 0.78 | 0.76 | 0.59 | 0.68 | Excellent |
SNA1 | 0.32 | 0.31 | 0.24 | 0.14 | 0.06 | 0.21 | Poor |
SNA2 | 0.32 | 0.32 | 0.32 | 0.29 | 0.20 | 0.29 | Poor |
SNA3 | 0.30 | 0.32 | 0.33 | 0.31 | 0.24 | 0.30 | Poor |
SNA4 | 0.28 | 0.32 | 0.32 | 0.29 | 0.20 | 0.28 | Poor |
SNA5 | 0.32 | 0.33 | 0.31 | 0.23 | 0.12 | 0.26 | Poor |
SNA6 | 0.33 | 0.30 | 0.20 | 0.10 | 0.04 | 0.19 | Poor |
SNA7 | 0.32 | 0.33 | 0.30 | 0.21 | 0.11 | 0.26 | Poor |
SNA8 | 0.32 | 0.33 | 0.29 | 0.19 | 0.10 | 0.25 | Poor |
SNA9 | 0.32 | 0.32 | 0.26 | 0.15 | 0.07 | 0.22 | Poor |
SNA10 | 0.33 | 0.27 | 0.17 | 0.08 | 0.03 | 0.18 | Poor |
SNA11 | 0.32 | 0.30 | 0.22 | 0.11 | 0.05 | 0.20 | Poor |
3.6 Item Characteristic, Item Information, And Error Curves
The x-coordinate represents ability, the y-coordinate represents the probability of choosing this option, and A represents the slope of the item characteristic curve (ICC;also known as the distinction parameter) on the ICC). B represents the difficulty of the items; the greater the difficulty, the better the level of health. Option 1 represents the entry of minimum intensity, option 5 represents the entry of the highest intensity, and the remaining three options (2–4) were essentially normally distributed(19). As shown in Fig. 1 and Fig. 2, for the entry GSS2 item characteristic curve and the curve of item information, the item basic satisfied the distribution of the item characteristic curve, and with an improvement in the level of ability, patients chose a high option with a growing probability of item information curve displaying scores of 1 to the largest amount of information (approximately 0.8). The total item information curve reflects the extent to which all items of the scale as a whole can provide accurate assessments of subjects with different levels of traits. The horizontal coordinate represents the project difficulty (corresponding to the characteristic level of the subject), the left vertical coordinate represents the amount of information, the right vertical coordinate represents the standard error, and the red dotted line represents the standard error of the project information function. The steeper the project information curve, the more the coverage area, indicating that the project could provide more accurate trait level estimation for a larger range of subjects. Figure 3 shows the total information curve in the GSO field. The maximum amount of information was close to 4.5, and the standard error was close to 0.6.