Ideally, a test should contain items with difficulty parameters well distributed across the full range of the latent phenotype and with good resolution (Figure 3).
Data collection was performed using questionnaires containing items with closed as well as open-ended answers.
It is based on physical modeling of a given freeform surface by a combination of items with regular geometry, well calibrated on their dimensions and form.
The tool demonstrated reasonable inter-rater reliability despite minimal requirements for evaluator training and displayed evidence of good internal structure, with related scale items correlating well with each other.
This is a short, validated tool comprising 24 items, with six subscales (physical well - being, emotional well - being, self - esteem, family, friends and school ).
Kinder Lebensqualitätsfragebogen (KINDL) questionnaire for the assessment of health-related QoL [ 24 ]: This is a short, validated tool comprising 24 items, with six subscores (physical well-being, emotional well-being, self-esteem, family, friends and school).
All items correlated well with their respective domains in confirmatory factor analysis.
Most data items correspond well, with discrepancies being mainly due to differing interpretations and definitions [ 10].
All item-total correlations were above 0.3, indicating that individual items correlate well with the total scale.
As shown in Table 3 no single item significantly impacted the overall scale internal consistency and all items correlated well with the overall score.
