Risk assessment can be quantitative or qualitative. The output of a quantitative risk assessment will typically be
a number, such as cost impact ($) per unit time. The number could be used to prioritize a series of items that
have been risk assessed. Quantitative risk assessment requires a great deal of data both for the assessment of
probabilities and assessment of consequences. Fault tree or decision trees are often used to determine the probability
that a certain sequence of events will result in a certain consequence. Qualitative risk assessment is less
rigorous and the results are often shown in the form of a simple risk matrix where one axis of the matrix represents
the probability and the other represents the consequences. If a value is given to each of the probability
and a consequence, a relative value for risk can
be calculated.