# concurrent states

I plan to use TraMineR for a research study on student course-taking patterns in secondary schools. For instance – Algebra, Geometry, Algebra II, etc. – where each course is a state. I wondered how to handle instances where students take two courses at once (say Algebra and Geometry in the same year)? Since I am considering each course a state – this would mean that there would be concurrent states in one year.

Can this be handled in TraMineR?

TraMineR has no specific feature to dealing with such combinations of states.
A solution is to extend the alphabet with combinations of states by adding, for example, Geometry.Algebra to the list of possible states. Of course, if you intend to compute dissimilarity between sequences you will have to suitably set the substitution costs. E.g., the cost for substituting Algebra to Geometry.Algebra could be set at half the cost for substituting Algebra to Geometry. You could try to systematize this with the method "FEATURES" of the seqcost function of TraMineR (>= v 2.0-5).