High Quality Content by WIKIPEDIA articles! In decision theory and economics, ambiguity aversion (also known as uncertainty aversion) describes an attitude of preference for known risks over unknown risks. People would rather choose an option with fewer unknown elements than with many unknown elements. It is demonstrated in the Ellsberg paradox (i.e. that people prefer to bet on an urn with 50 red and 50 blue balls, than in one with 100 total balls but where the number of blue or red balls is unknown). There are a number of choices involving uncertainty and normally they can be classified in two categories: risky and ambiguous events. Risky events have a certain probability for a given outcome. Ambiguous events have a much greater degree of uncertainty. This includes the uncertainty of outcome and also the probability of an event occurring or the payoff associated with such events. The reaction is behavioral and still being formalized. Ambiguity aversion can be used to explain incomplete contracts, volatility in stock markets, and selective abstention in elections (Ghirardato Marinacci, 2001)