Unidimensionality is always been described as a specific type of measurement scales. It has only one (uni) dimension. Unidimensionality refers to the existence of a single trait or construct underlying a set of measures (Gerbing & Anderson, 1988).
The confirmatory factor analysis (CFA) assess the internal and external consistency of unidimensionality implied by a multi indicator measurement model that cannot be assessed by Cronbach Alpha and item to total correlation. The additional unidimensionality test were added to suit SEM analysis.
Unidimensionality can be achieved if the factor loadings of the measuring items for the respective latent construct are acceptable. Factor loading which is too low should be deleted for the model to be unidimensionality.
