Value at risk is the unexpected loss, and tolerance level is the probability of
loss occurrence that is more than the maximum of the predicted losses.
Therefore, to obtain VaR it can be appropriate to focus on the left tail of the
return distribution (loss distribution). So VaR is defined as the highest loss over
a certain period of time at a given confidence level. Confidence level in VaR
definition depends on risk aversion level of individuals involved with the issue.