Introduction
Methods
Development of a candidate item bank
A community and hospital-based survey
Item bank calibration
Results
Frequency (%) | |
---|---|
N = 503 | |
Age | |
21–34 years old | 122 (24.3) |
35–49 years old | 173 (34.4) |
50 and above | 208 (41.4) |
Gender | |
Male | 240 (47.7) |
Female | 263 (52.3) |
Ethnic Group | |
Chinese | 171 (34.0) |
Malay | 169 (33.6) |
Indian | 163 (32.4) |
Health1 | |
Well | 180 (36.5) |
Mildly unwell | 62 (12.6) |
Unwell | 251 (50.9) |
Marital status | |
Single | 110 (21.9) |
Married | 364 (72.4) |
Separated/divorced/widowed | 29 (5.8) |
Completion of secondary education (10 years of education) | |
Yes | 422 (83.9) |
No | 81 (16.1) |
Item analyses
IRT assumptions of unidimensionality and local independence
Unidimensionality | ||||
---|---|---|---|---|
Approach | Criterion | Reference | Results | Criterion met? |
EFA | Percentage of variance accounted for by first factor > 20% | PROMIS [16] | 18.1% | No |
Ratio of first to second eigenvalues > 4.0 | PROMIS [16] | 8.01 | Yes | |
CFA | CFI > 0.95 | PROMIS [16] | 0.923 | No |
TLI > 0.95 | PROMIS [16] | 0.917 | No | |
RMSEA < 0.06 | PROMIS [16] | 0.098 | No | |
SRMR < 0.08 | PROMIS [16] | 0.081 | No | |
Bifactor analyses | ARPB < 10% | Muthén, Kaplan, and Hollis (1987) [33] | 3.6%§ | Yes |
General ECV > 0.70 | Reise, Bonifay and Haviland (2013) [17] | 0.805ǂ | Yes | |
OmegaH > 0.80 | 0.980¥ | Yes | ||
General ECV > 0.60 and OmegaH> 0.70 | Reise, Schienes, Widaman and Haviland (2013) [15] | Yes | ||
Local Independence | ||||
Residual correlation matrix | Average absolute residual correlations < 0.10 | PROMIS[16] | 0.067 | Yes |
Percentage of residual correlations above 0.20 | Artmann et al. 2010 [18] | 1.84% | No threshold given | |
(8 of 435) |
Item ID | Item | Single-factor CFA | Exploratory Bifactor Analysis – general factor loadings | |||
---|---|---|---|---|---|---|
2 specific factors | 3 specific factors | 4 specific factors | Mean Item ECVs§ | |||
SQ01 | I have a good relationship with my family | 0.931 | 0.900 | 0.895 | 0.908 | 0.884 |
SQ32 | I have someone to talk to about my problems | 0.792 | 0.803 | 0.796 | 0.801 | 0.952 |
SQ39 | I live harmoniously with others | 0.790 | 0.800 | 0.796 | 0.798 | 0.941 |
SQ11 | I communicate well with my family | 0.940 | 0.921 | 0.915 | 0.926 | 0.918 |
SQ02 | I participate in family activities | 0.757 | 0.769 | 0.765 | 0.769 | 0.952 |
SQ33 | I have someone who can provide me with information if I need it | 0.777 | 0.789 | 0.785 | 0.786 | 0.974 |
SQ10 | I take care of my family | 0.772 | 0.768 | 0.775 | 0.782 | 0.835 |
SQ40 | I communicate well with others | 0.841 | 0.843 | 0.847 | 0.844 | 0.847 |
SQ12 | I keep in touch with my family | 0.879 | 0.864 | 0.870 | 0.878 | 0.897 |
SQ07 | My family is willing to help with my daily tasks (e.g. shopping, giving me a ride, or helping me with household tasks) when I need it | 0.700 | 0.711 | 0.709 | 0.712 | 0.922 |
SQ16 | I keep in touch with my friends | 0.762 | 0.689 | 0.699 | 0.671 | 0.598 |
SQ34 | I know that I have someone to help me if I have financial difficulties | 0.680 | 0.667 | 0.661 | 0.652 | 0.826 |
SQ41 | I keep in touch with others | 0.812 | 0.780 | 0.787 | 0.768 | 0.788 |
SQ04 | I feel loved and cared for by my family | 0.858 | 0.849 | 0.855 | 0.866 | 0.900 |
SQ08 | My family is willing to give me information when I need it | 0.835 | 0.828 | 0.831 | 0.841 | 0.895 |
SQ17 | I communicate well with my friends | 0.766 | 0.756 | 0.770 | 0.754 | 0.844 |
SQ43 | I am able to socialize with others | 0.718 | 0.702 | 0.717 | 0.701 | 0.798 |
SQ45 | I feel loved and cared for | 0.852 | 0.863 | 0.871 | 0.872 | 0.971 |
SQ31 | I have someone I can go to for advice if I need it | 0.763 | 0.757 | 0.744 | 0.749 | 0.703 |
SQ35 | I give help to others | 0.712 | 0.700 | 0.703 | 0.693 | 0.813 |
SQ44 | I have someone who would spend time with me when I need company | 0.827 | 0.822 | 0.815 | 0.811 | 0.858 |
SQ05 | Overall, my family supports me when I need it | 0.835 | 0.826 | 0.820 | 0.833 | 0.858 |
SQ18 | I have gatherings with my circle of friends | 0.686 | 0.630 | 0.628 | 0.606 | 0.607 |
SQ15 | I give support to my friends | 0.674 | 0.647 | 0.651 | 0.635 | 0.771 |
SQ37 | I get along well with others | 0.750 | 0.759 | 0.763 | 0.761 | 0.967 |
SQ06 | My family is willing to listen when I need to talk about my worries and problems | 0.788 | 0.783 | 0.774 | 0.788 | 0.830 |
SQ20 | I spend time with my friends | 0.670 | 0.598 | 0.600 | 0.576 | 0.536 |
SQ48 | Overall, I am satisfied with the support I get from my friends | 0.741 | 0.715 | 0.695 | 0.680 | 0.712 |
SQ50 | Overall, I am satisfied with the support I give to others | 0.753 | 0.732 | 0.705 | 0.694 | 0.662 |
SQ51 | Overall, I am satisfied with how well I communicate with others | 0.797 | 0.793 | 0.770 | 0.767 | 0.806 |
Bifactor analysis statistics | ||||||
ARPB | 2.6 | 2.8 | 3.6 | |||
ECV | 0.855 | 0.828 | 0.805 | |||
OmegaH | 0.983 | 0.985 | 0.984 | |||
Hancock and Mueller’s H | 0.995 | 0.992 | 0.985 | |||
Average ECVs of specific factors | 0.072 | 0.057 | 0.049 |
IRT calibration and fit
Item ID | Mean | Item-theta correlation | Cronbach’s alpha if deleted | IRT | GRM item fit p-value | ||||
---|---|---|---|---|---|---|---|---|---|
Discrimination | B1 | B2 | B3 | B4 | |||||
SQ01 | 4.584 | 0.711 | 0.961 | 2.072 | −2.43 | −2.18 | −1.75 | 0.55 | 1.000 |
SQ32 | 4.35 | 0.713 | 0.961 | 1.509 | −2.74 | − 2.25 | − 1.39 | −0.09 | 0.734 |
SQ39 | 4.531 | 0.673 | 0.962 | 1.378 | −3.54 | −3.18 | − 2.06 | − 0.30 | 0.193 |
SQ11 | 4.546 | 0.754 | 0.961 | 2.081 | −2.58 | − 2.29 | −1.71 | − 0.42 | 1.000 |
SQ02 | 4.175 | 0.672 | 0.962 | 1.179 | −2.63 | −1.97 | − 1.13 | 0.06 | 0.711 |
SQ33 | 4.286 | 0.71 | 0.961 | 1.266 | −2.94 | − 2.40 | −1.33 | 0.07 | 0.714 |
SQ10 | 4.493 | 0.629 | 0.962 | 1.191 | −2.76 | − 2.29 | −1.81 | − 0.46 | 0.086 |
SQ40 | 4.483 | 0.713 | 0.961 | 1.418 | −4.16 | −3.00 | −1.74 | −0.23 | 0.997 |
SQ12 | 4.553 | 0.702 | 0.961 | 1.608 | −2.77 | −2.30 | −1.65 | −0.53 | 0.981 |
SQ07 | 4.171 | 0.641 | 0.962 | 1.021 | −2.89 | − 2.09 | −1.17 | 0.12 | 0.446 |
SQ16 | 4.125 | 0.627 | 0.962 | 0.963 | −3.5 | −2.36 | −1.08 | 0.29 | 0.226 |
SQ34 | 3.917 | 0.607 | 0.962 | 0.95 | −2.33 | −1.68 | −0.79 | 0.29 | 0.000 |
SQ41 | 4.235 | 0.692 | 0.961 | 1.23 | −3.16 | −2.24 | −1.13 | 0.04 | 0.030 |
SQ04 | 4.545 | 0.692 | 0.961 | 1.54 | −2.64 | − 2.28 | −1.65 | −0.53 | 0.888 |
SQ08 | 4.453 | 0.711 | 0.961 | 1.435 | −2.78 | −2.29 | −1.55 | −0.30 | 0.997 |
SQ17 | 4.376 | 0.66 | 0.962 | 1.153 | −3.77 | −2.88 | −1.50 | −0.11 | 0.613 |
SQ43 | 4.326 | 0.607 | 0.962 | 1.007 | −3.95 | −2.74 | −1.47 | −0.08 | 0.229 |
SQ45 | 4.517 | 0.72 | 0.961 | 1.634 | −2.83 | −2.41 | −1.63 | −0.38 | 0.828 |
SQ31 | 4.266 | 0.675 | 0.961 | 1.229 | −2.73 | −2.32 | −1.32 | 0.02 | 0.630 |
SQ35 | 4.26 | 0.642 | 0.961 | 1.044 | −3.42 | −2.57 | −1.29 | 0.06 | 0.402 |
SQ44 | 4.292 | 0.734 | 0.961 | 1.464 | −3.24 | −1.97 | − 1.22 | −0.04 | 0.060 |
SQ05 | 4.503 | 0.674 | 0.961 | 1.445 | −2.5 | −2.36 | −1.58 | −0.48 | 0.546 |
SQ18 | 3.817 | 0.6 | 0.962 | 0.863 | −2.96 | −1.75 | −0.62 | 0.64 | 0.073 |
SQ15 | 4.024 | 0.586 | 0.962 | 0.896 | −3.01 | −2.56 | −1.04 | 0.54 | 0.191 |
SQ37 | 4.475 | 0.66 | 0.962 | 1.221 | −4.35 | −3.36 | −1.89 | −0.18 | 0.949 |
SQ06 | 4.345 | 0.673 | 0.961 | 1.256 | −2.56 | −2.19 | −1.41 | −0.18 | 0.999 |
SQ20 | 3.787 | 0.575 | 0.962 | 0.794 | −3.48 | −1.97 | −0.51 | 0.80 | 0.005 |
SQ48 | 4.167 | 0.663 | 0.962 | 1.138 | −2.75 | −2.11 | −1.14 | 0.13 | 0.078 |
SQ50 | 2.765 | 0.074 | 0.969 | 0.157 | −3.95 | −0.11 | 2.26 | 5.29 | 0.000 |
SQ51 | 3.974 | 0.656 | 0.962 | 1.05 | −2.73 | −2.20 | −1.01 | 0.73 | 0.321 |
Differential item function detection
Concurrent validity evaluation
Self-report of global health | N (%) | SR theta score means# (95% CI) | Spearman’s rho |
---|---|---|---|
(95% CI) | |||
Excellent | 32 (6.4) | 0.29 (−0.12 to 0.70) | −0.279 |
Very Good | 119 (23.7) | - 0.05 (−0.33 to 0.23) | (−0.359, − 0.196) |
Good | 255 (50.7) | - 0.26 (−0.51 to − 0.02) | |
Fair | 77 (15.3) | −0.71 (−1.02 to − 0.39) | |
Poor | 20 (4.0) | −1.32 (− 1.78 to − 0.86) |