
Time Series Models 201
probabilities themselves uncertain (which, in reality, they typically are). An
important requirement is that all the transition probabilities in every row
sum to one. Nested logical statements (e.g., IF(AND), IF(OR), etc.) can be used
to model the transition from one period to the next. While it is fairly straight-
forward to model the transition of the 100 accounts to the next month, it
quickly becomes very cumbersome within Excel to model the evolution of a
large number of states or a large number of time periods.
ModelRisk contains a feature that easily models a Markov Chain. Markov6.
xlsx shows such a model for