1. A method for validating data, said method comprising: a processor of a data processing system generating warehouse data in a data warehouse by transforming source data in a data source into the warehouse data via an Extract-Transform-Load (ETL) transformation model; said processor generating a data cube by transforming the warehouse data in the data warehouse into the data cube via an On-Line Analysis Processing (OLAP) transformation model; said processor generating a report multi-dimensional data set (MDS 1 ) from the data cube via a data cube query of the data cube; said processor generating a reference multi-dimensional data set (S) from the source data via a source data query of the source data, said source data query corresponding to the data cube query; and said processor determining whether MDS 1 matches S; wherein if said determining whether MDS 1 matches S comprises determining that MDS 1 does not match S, then the method further comprises said processor performing an OLAP inverse transformation on MDS 1 to generate an OLAP multi-dimensional data set (MDS 2 ) and said processor determining whether MDS 2 matches S; wherein if said determining whether MDS 1 matches S comprises determining that MDS 1 does not match S and said determining whether MDS 2 matches S comprises determining that MDS 2 does not match S, then said processor performing an ETF inverse transformation on MDS 2 to generate an ETL multi-dimensional data set (MDS 3 ) and said processor determining whether MDS 2 matches MDS 1 and said processor determining whether MDS 3 matches S; wherein if said determining whether MDS 1 matches S comprises determining that MDS 1 does not match S and said determining whether MDS 2 matches S comprises determining that MDS 2 does not match S and said determining whether MDS 3 matches S comprises determining that MDS 3 does not match S, then said processor determining whether MDS 3 matches MDS 2 ; wherein if said determining whether MDS 1 matches S comprises determining that MDS 1 does not match S, then the method further comprises ascertaining that a data error exists such that said ascertaining ascertains that the data error is an OLAP model error in the OLAP transformation model, an ETL model error in the ETL transformation model, a dirty data error comprising an error in the source data and/or erroneous data in the data warehouse, the ETL model error and/or the dirty data error, the OLAP model error and the ETL model error, or the OLAP model error and the ETL model error and the dirty data error; wherein if said determining whether MDS 1 matches S comprises determining that MDS 1 matches S, then the method further comprises determining that a normal data condition exists such that the OLAP model error does not exist, the ETL model error does not exist, and the dirty data error does not exist.