Risk derives its subjectivity through the variation in its level of occurrence, the likelihood of its occurrence and severity of impact. The World Bank classifies risks by the level they occur (micro, meso and macro) and by the nature of the event (natural, social and environmental, among others). Risks at the micro level affect individuals and households. These are called idiosyncratic risks, since the correlation with other agents is close to zero. Death, illness and aging fall under this category. Meso and macro risk affect communities and countries. These risks, also called covariant, are difficult to insure, since the correlation between individual risk is greater than zero. Examples of these can of risks are unemployment, earthquakes, floods or wars. Finally, risks can be distinguished by severity and frequency. The likelihood of getting a flu is very high (high frequency), but its costs are low (low severity). The contrary happens with a tsunami: it is a very unlikely event (low frequency), but if it happens, could wipe out all assets and lead to death (high severity).
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