A Ragged Hierarchy provides for a Hierarchy structure in which a Member exists on what one would typically assume to be a Parent Member level.
As an example: consider a Salesperson Hierarchy that has two top-level Aggregates, Foreign and Domestic. Assume that the Domestic aggregate is further broken down into Regions (East, Midwest and Southwest), whereas the Foreign aggregate does not include that additional level of depth.
A salesperson in the Domestic hierarchy would exist under one of the indicated regions; a salesperson in the Foreign hierarchy, at the same level as the Domestic salesperson, would be directly under the Foreign Member–an example of a ragged hierarchy.