Parallel coordinate plot (seqpcplot) using TraMineR: How are event sequences without any transition represented?

Question

I'm using the R packages TraMineR to compute and analyze the event state sequences. My alphabet consists of 7 states: however, some individuals do not experience any transition along the 84 months considered, staying always in the same state. The event state sequences for these cases are, for example:

[1] (full_time)-84
[2] (part_time)-84

If one of those sequences is at the same time one of the most frequent, how is it represented by the command seqpcplot? It is simply ignored because no transition appears along the sequence and the plots show only the most frequent trajectories of those who change state?

Thank you very much.

Answer 1

Empty zero-event sequences are represented with a black square south-west of the bottom left translation zone.

However, the two event sequences given in your example are NOT zero-event sequences. They each have a start event, namely full_time and part_time. Such patterns are represented with a square on the first coordinate axis, respectively in regard of full_time and part_time.

If you don't use the embedding trick, they will appear as isolated squares with size proportional to their frequencies. With option ltype = "non-embeddable", the pattern will be embedded in some other pattern starting with the same event. This is reflected with the start square bigger than the next one on the same path.

So in your case, if say the first one is the most frequent pattern: With ltype = "unique", you should have a relatively large isolated square next to full_time on the first coordinate. With ltype = "non-embeddable", you should have an even bigger square next to full_time, but with a path continuing to some point on the second coordinate where you should observe a smaller square (where it represents fewer cases than at the start point).

Hope this helps.