To evaluate item characteristics, item difficulty indices (defined as percentage of agreements among all responses), inter-item-correlations and corrected item-total-correlations were computed, and the items were analysed for an increase of the scale's reliability coefficient (Cronbach's α) in case of item deletion.
Especially in case of item (14) providing participant's information about the patient recruitment, the item was coded as "yes" only when the flow diagram was given or explicitly described (i.e. the number of controls per case was specified and the matching variables were clearly stated).
DCMS said it considered such bans in cases of items which have been in the UK for more than 50 years.
In case of missing items in the BFS or the QLQ-C30, multi-item scores were calculated as the mean of non-missing items if at least half of the items from the corresponding scale had been completed.
As predictable, for the two items relating to accessibility of the service in case of emergency (items 5 and 6, Appendix [see Additional File 1]) the number of 'does not apply' responses was high (30.7% and 45.0%).
In case of missing items person-mean (prorated) imputation was conducted for up to a third of items in the scales.
In case of missing items, they are given the value which is the mean of the rest of the items which have been answered by the patient.
We plan to extend the comparison for similarity metrics applied for non-dichotomous data and/or using SRD calculations in case of repeated items (degeneracies).
In case of food items, 25 grams of each sample was weighed and transferred to sterile flask containing 100 ml of phosphate buffer saline (PBS).
This means that individuals with different QL, in case of the item present good discrimination, they have a tendency to register different responses in this item.
In case of missing item scores, we will explore the possibility of a single imputation technique.
