In simulation 1, half of the factor loadings equalled.3 (unreliable items), and half to.9 (reliable items).
They remark that the context, selection and sequence of questions, considering both item diversity and clinical diversity, may produce sample-dependent item difficulty estimates and therefore unreliable item-dependant estimates of patient ability.
Cella and Chang [ 42] also remarked that the context, selection and sequence of items, considering both item diversity and clinical diversity, may produce sample-dependent item difficulty estimates and, therefore unreliable item-dependent estimates of patients' severity of illness.
Unreliable items (defined as point biserial correlation scores below 0.15) were revised or removed.
Unreliable items those with limited variability or high levels of missing data were eliminated.
During the development of MDS instruments, unreliable items were progressively eliminated resulting in increasing reliability estimates over time [ 25, 81].
Unreliable items that elicit inconsistent responses from an individual are of no value, as are items that are frequently missed out, perhaps due to lack of clarity in the wording or lack of relevance to a significant number of individuals.
Eighteen items were reliably audited and displayed adequate environmental variability, 25 items proved unreliable, and 69 items lacked adequate environmental variability.
Another view (not supported by our data) is that the large extended family system probably makes this item unreliable in our setting.
Validation of the instrument follows, to assess coherence across the items and inform the removal of poorly discriminating, unreliable or invalid items [ 2].
