Hello,

I was thinking that this was the reason.

I have prepared a little spread sheet of my method if you wouldn't mind looking at it?

http://dl.dropbox.com/u/54057365/All/tpm3.JPG
A sample of recorded values are in Col A and you will see a frequency a matrix and transitional probability matrix.

As you pointed out row 2 is incorrect.

However the next time the car drives the route a value of 2 could be recorded. And in order to get the average of the two matrices then they would need to be the same size, correct?

Could you suggest a solution to this?

Many thanks

John