(5)The severity of an economic downturn should be specified by reference to the most severe 12-month values observed over an appropriate historical time-span for the set of economic indicators characterising the nature of a downturn for the particular type of exposures under consideration. For each economic indicator in the set, the most severe 12-month value should be used because it strikes a balance between stability and identification of the most severe conditions observed in an appropriate time-span. This approach was chosen for simplicity of the 12-month view and also because a longer average could potentially dilute adverse conditions observed on an economic indicator. More frequent values, for example quarterly values, could be subject to seasonal influences. On the other hand, less frequent values, for example values representing 36-month averages, could hide severe conditions.