Reliability analysis of quality of life instruments for cancer patients-gastric cancer (QLICP-GA) based on generalizability theory

Objective: To evaluate the reliability of QLICP-GA (quality of life instruments for cancer patients-gastric cancer) scale by using generalizability theory, and to provide the references in order to revise and improve this scale. Methods: The mean squares of person (p), item (i) and the person-by-item interaction effect (pi) were calculated by using the module of UNIANOVA under the menu of General Linear Model in SPSS software. Furthermore, the generalizability coefficients and indexes of dependability were calculated in order to assess the reliability of QLICP-GA scale. Results: The largest source of variation in every domain was due to person-by-item interaction. The variances accounted for by person were large, while the variation accounted for by item was minimal. Generalizability coefficients of five domains were 0.774 (physical domain), 0.854 (psychological domain), 0.670 (social domain), 0.717 (common symptom and side effect domain), and 0.696 (specific domain), respectively. Conclusion: Physical domain, psychological domain and common symptom and side effect domain in QLICP-GA have good reliability. However, social domain and specific domain have acceptable reliability. Social domain should be emphasized when this scale will be revised and improved in future. The number of items of social domain should be added from 6 to 8 or 10. Secondly, the number of items of specific domain may be slightly added from 7 to 9. DOI:10.3781/j.issn.1000-7431.2013.05.008