Here a few reasons why. They are likely to appear much more complicated. There will often be a sequence of decisions extending into an uncertain future. Every decision we make involves some degree of uncertainty . The evidence on which any decision is based inevitably relates to the past, whilst the consequence of our present actions always lie in the future.
Uncertainty comes in degrees, sometimes small, sometimes very large.
The final result of taking any decisions is likely to be affected by factors outside the control of the decision maker . The object of the exercise will rarely be as simple as minimising costs. The very concept of a single best result may be inappropriate . The ideal decision at any stage may be the one that leaves the decision maker most flexibility about the future. Decision analysis provides systematic methods of dealing with the difficulties and complexities.