However, the use of HAMD has not been exempted from criticism what has lead to the development of new scales that are expected to be more sensitive for change, such as the Montgomery Åsberg depression rating scale (MADRS).
Rasch analysis has been used in rheumatology in the development of new scales [ 19, 20], to test the psychometric properties of existing scales [ 21, 22] and for cross-cultural validation of patient outcome measures [ 14, 23, 24].
These approaches are increasingly being used in the development of new scales and in the improvement of existing scales that measure latent traits such as depression, by establishing their fundamental measurement ability [ 23].
For the development of new scales, traditionally, a factor extraction method based on Eigenvalues is used [ 10, 11] to explore the number of domains, and the strength of association of items within domains.
The current study will address the following research questions by testing the scale against the requirements of the Rasch measurement model [ 38] (see Methods for full description) which is based on the Item Response Theory [ 39] and is increasingly used in the development of new scales and in the improvement of existing scales [ 40]: 1.
Sequencing of complete bacterial genomes led to the development of new large-scale technologies, such as bioinformatics, proteomics and DNA microarrays.
Therefore, there is a need for the development of new valid scales or assessment strategies showing better inter-observer reliability.
In recent years, efforts to identify imprinted genes have been enhanced greatly by the development of new genome-scale technologies for epigenomic profiling (for example, [ 50]) and by the cataloguing of known imprinted genes [ 12, 51].
Despite the development of new rating scales and visual methods, then, the boundaries between what Martin Roth called 'senile dementia and its borderlands' remain blurred, and psychiatrists acknowledge that 'clinical judgements' remain vital in these instances (ibid.: 27; Roth, 1980).
Thus, IRT can facilitate the development of new items and scales to improve exiting measures.
