PROMIS T-scores were used (mean=50; standard deviation=10), and descriptive statistics were calculated for gender, age and education subgroups. Scores for the legacy instruments (SF-36 (Ware, et al., 2000 ) and FACT-GP (Brucker, et al., 2005 (link))) were calculated using the developers’ guidelines.
Criterion validity (Scientific Advisory Committee of the Medical Outcomes Trust, 2002 (link)) for the English data was evaluated by calculating Pearson correlation coefficients between PROMIS T-scores, three SF-36 subscales (Social Functioning, Role-Emotional and Role-Physical (Ware, et al., 2000 )), and the FACT-GP Functional Well-being subscale (Brucker, et al., 2005 (link)). Correlations with the SF-36 and FACT-GP were hypothesized to be high for PROMIS Social Function domains since all of these measures focus on perceived function and abilities. Correlations for PROMIS Social Relationships were expected to be more moderate, with Social Isolation being negatively associated, and Social Support being positively associated, with the criterion measures. Construct validity (Scientific Advisory Committee of the Medical Outcomes Trust, 2002 (link)) was evaluated by comparing mean scores between respondents with and without comorbidities, and between English online panel respondents and those from the clinical samples, using independent group t-tests. Effect sizes were calculated as the mean difference between groups divided by the overall standard deviation, and interpreted in terms of a minimally important difference in patient-reported outcome measures (0.33) (Yost & Eton, 2005 (link)). Respondents without comorbidities and those from the online panel were hypothesized to have higher PROMIS Social Function scores than the comparison groups.
Criterion validity (Scientific Advisory Committee of the Medical Outcomes Trust, 2002 (link)) for the English data was evaluated by calculating Pearson correlation coefficients between PROMIS T-scores, three SF-36 subscales (Social Functioning, Role-Emotional and Role-Physical (Ware, et al., 2000 )), and the FACT-GP Functional Well-being subscale (Brucker, et al., 2005 (link)). Correlations with the SF-36 and FACT-GP were hypothesized to be high for PROMIS Social Function domains since all of these measures focus on perceived function and abilities. Correlations for PROMIS Social Relationships were expected to be more moderate, with Social Isolation being negatively associated, and Social Support being positively associated, with the criterion measures. Construct validity (Scientific Advisory Committee of the Medical Outcomes Trust, 2002 (link)) was evaluated by comparing mean scores between respondents with and without comorbidities, and between English online panel respondents and those from the clinical samples, using independent group t-tests. Effect sizes were calculated as the mean difference between groups divided by the overall standard deviation, and interpreted in terms of a minimally important difference in patient-reported outcome measures (0.33) (Yost & Eton, 2005 (link)). Respondents without comorbidities and those from the online panel were hypothesized to have higher PROMIS Social Function scores than the comparison groups.
