You can assign a certainty factor with each of your answers in the input window. This factor is a measure of how certain you are about your answer.

Certainty factors are very important in the interpretation of output results. They are used to weight the different answers.

The certainty factor ranges from 0 - 100 per cent.

The default certainty factor is 100 which means that you are certain about your answer.
If your answer is uncertain, you may change the certainty factor value; try to avoid assigning certainty factors of less than 60 for the answer in your input data, as this will reduce the strength of the conclusion.