Basing all information on project management concepts, a common assumption following the completion of a project would be that the sun would rise the...

Basing all information on project management concepts, a common assumption following the completion of a project would be that the sun would rise the next day. Suppose for a moment the sun did not rise. The severity of this risk would threaten not only the completion of this project but most other projects. In other words, the risk posed by the sun not rising is extremely high; however, the likelihood of that happening is relatively small. On the other hand, consider a different sort of risk. Consider that one of the billing system database servers has been destroyed. The likelihood of this happening is considerably higher than the likelihood of the sun not rising. Unless the database was not recently backed up, the severity of this risk is relatively low. In other words, neither of these risks rises to a level that would threaten the completion of the project.

What the are with differences between qualitative and quantitative risk analysis and when is each of analysis appropriate?