Exploratory factor analysis among items with different measurements

Question

I intend to do an exploratory factor analysis among items that have different types of measurements: for example, some items have bounded scales (1-100%), some items take small and other large values (different units indeed, such as dollars or hours).

I've been reading a lot and haven't found a negative answer, i.e. that it is not possible to do such analysis with such varied types of items; however, every example I came across is based on items that take the same values (e.g. 4-value likert scales from questionnaires).

In sum, does anyone have a clear answer (and reference?) on this matter?

Answer 1

EFA is based on the correlation matrix of your items. That means, scale differences between items are not a problem, as the correlation is a scale-free index. You should check your variables for other problems (e.g., ceiling or floor effects in your bounded variables), but different units do not pose a problem.

Answer 2

I do not have a clear answer but it seems that the problem you describe is a small subset of what is usually called “common method variance”. You might find more information on this and some further references in:

• Podsakoff, P.M., MacKenzie, S.B., Lee, J.-Y., & Podsakoff, N.P. (2003). Common method biases in behavioral research: A critical review of the literature and recommended remedies. Journal of Applied Psychology, 88 (5), 879–903.