Comparison of the Performance of Varimax and Promax Rotations: Factor Structure Recovery for Dichotomous Items

Nonlinear factor analysis is a tool commonly used by measurement specialists to identify both the presence and nature of multidimensionality in a set of test items, an important issue given that standard Item Response Theory models assume a unidimensional latent structure. Results from most factor-analytic algorithms include loading matrices, which are used to link items with factors. Interpretation of the loadings typically occurs after they have been rotated in order to amplify the presence of simple structure. The purpose of this simulation study is to compare the ability of two commonly used methods of rotation, Varimax and Promax, in terms of their ability to correctly link items to factors and to identify the presence of simple structure. Results suggest that the two approaches are equally able to recover the underlying factor structure, regardless of the correlations among the factors, though the oblique method is better able to identify the presence of a "simple structure." These results suggest that for identifying which items are associated with which factors, either approach is effective, but that for identifying simple structure when it is present, the oblique method is preferable.     

iPod Shuffle not Random

This article discusses the behaviour of a sequence of events under random choice and under a restriction of randomness. Outline lesson plans at three different levels are suggested.     

Realist and relational perspectives on graduate identity and employability: a response to Hinchliffe and Jolly

This article responds to that by Hinchliffe and Jolly, published in an earlier issue of this journal, exploring graduate identity and employability. Their article espousedly draws upon the conceptualisation of graduate identity, as formulated by this present author. This article argues that Hinchliffe and Jolly have given insufficient attention to different modes of conceptualisation, the realist and the relational, that are key to differentiating the original use of the term ‘graduate identity’ from uses where that term is conflated with ‘graduateness’. After exploring realist and relational perspectives, the article considers possible reformulation of the study by Hinchliffe and Jolly, to enhance its contribution to research from a relational perspective.