The first aspect in the development process is to examine what others have
done in order to obtain a proper theoretical knowledge base, in addition to
which radiographer competence should be conceptualised. Then, the items in
the categories and sub-categories must be selected on the basis of theoretical
knowledge. Furthermore, the categories must be described and a statement
made before the grouping of the categories can be decided. Face and content
validation of an instrument is of great importance in order to collect accurate
and relevant data. One of the most appropriate methods of achieving this is to
use the criteria recommended by Lynn.141 These criteria include content,
relevance, clarity, concreteness, understandability and readability of the scale.
To judge the relevance of the items both individually and as a set, experts have
to rate the content relevance of each item using a 4-point rating scale (from 1
“not relevant”, to 4 “very relevant”). In addition, experts must identify
important areas not included in the instrument, items dealing with
competencies and the association between the items and competencies. Finally,
missing items or competencies and suggested additional items need to be
identified.