Psychometric property | Definition/test | Criteria |
---|---|---|
Acceptability | Quality of data; assessed by completeness of data and score distributions. |
|
Reliability: internal consistency | Extent to which items in a scale measure the same construct (such as homogeneity of the scale); assessed by Cronbach's α, item-total correlations, and value of α if an item is deleted from a scale. |
|
Tests of scaling assumptions | Evidence that an item belongs in its own scale and not another scale (item convergent and discriminant validity). |
|
Construct validity (within scale analyses) | Evidence that each scale measures a single construct and that items can be combined to form scales; assessed on the basis of evidence of good internal consistency, factor analysis and correlations between scale scores. |
|
Construct validity (analyses against external criteria): convergent and discriminant validity | Evidence that scales are correlated with other measures of the same or similar construct, and not correlated with other measures of different constructs; assessed on the basis of correlations between CROQ, EQ-5D-3L, and age and sex. |
|
Construct validity (analyses against external criteria): hypothesis testing | Evidence that scales differentiate known groups; assessed by comparing CROQ scores between groups hypothesised to differ. |
|
Responsiveness | Ability of scales to detect clinically important change over time between Q1 and Q2. Assessed by effect sizes (mean change score between prerevascularisation and postrevascularisation divided by the SD of scores at pre-revascularisation). |
|
*Adapted from Schroter and Lamping 2004.3
CROQ, Coronary Revascularisation Outcome Questionnaire.