1. A method for providing a forecast, comprising: providing a multi-dimensional database storing data at a lowest level in a first dimension; calculating a first forecast at a level that is higher than the lowest level of a first dimension in the database; calculating a forecast for each category within the lowest level of the first dimension; aggregating a second forecast across a category at the lowest level of the first dimension based upon an aggregation of the calculated forecast for the category within the lowest level of the first dimension; determining a difference between the first forecast and the second forecast; and storing the difference in a dummy category at the lowest level of the first dimension.